MUUCSF Presentations


The American Society of Tropical Medicine and Hygiene (ASTMH)

Please click on conference to view abstracts presented.


2012, ATLANTA, GA, USA

Prasanna Jagannathan, Emmanuel Osilo, Mary Muhindo, Abel Kakuru, Emmanuel Arinaitwe, Bryan Greenhouse, Moses Kamya, Jordan Tappero, Grant Dorsey. The Tororo Child Cohort: A longitudinal study of malaria infection in the setting of insecticide treated bednets and artemisinin-based combination therapy.

 

Abstract presented at ASTMH, Atlanta Nov 2012.
Many reports have suggested that malaria transmission and incidence are decreasing in Africa in the setting of malaria control interventions, but longitudinal studies are lacking. We enrolled a cohort of 100 HIV unexposed children in a holoendemic area of high malaria transmission intensity in Uganda and followed them through 48 months of age. Children were enrolled over a nine-month period from 2007-2008, given ITN at enrollment, and received all care at a study clinic, including ACTs for smear-proven episodes of malaria. Routine assessments were performed monthly, including evaluation for asymptomatic parasitemia - defined as a positive smear in the absence of fever and not resulting in an episode of malaria within 7 days. We used a generalized additive model to evaluate the incidence of malaria and prevalence of asymptomatic parasitemia by age, calendar time and season. We calculated the relative risk of incident malaria by these parameters using generalized estimating equations with robust standard errors. Of 100 children enrolled, 79 reached 48 months of age; the mean age of enrollment was 5.52 months, and children were followed for a median of 3.46 years. A total of 1633 incident episodes of malaria were observed in this cohort, with a median incidence of 5.32 ppy (IQR 3.16-6.8) despite 98% compliance with ITNs. There were only 6cases of complicated malaria, all due to single convulsions. Malaria transmission was year-round, with two annual incidence peaks from Nov-Jan and Apr-Jul, corresponding to rainy seasons. Malaria incidence was stable (>6 ppy) until 30 months of age before declining. After adjusting for age and season, the relative risk of malaria increased by 50% from 2008 to 2011 (RR1.52, 95% CI 1.10-2.09). Asymptomatic parasitemia was uncommon (monthly prevalence above 10%), and was rarely detectable prior to 30 months of age. Despite ITNs and prompt treatment with ACTs, the incidence of malaria appears to be rising in Tororo. Additional malaria control interventions among young children living in high transmission settings are needed.


Kapisi J, Bigira V, Kinara S, Mwangwa F, Osterbauer B, Achan J, Kamya MR, Dorsey G. Malaria chemoprevention in a high transmission setting: A randomized controlled trial of monthly dihydroartemisinin-piperaquine versus monthly sulfadoxine-pyrimethamine versus daily trimethoprim-sulfamethoxazole versus no therapy for the prevention of malaria.

 

Abstract accepted to ASTMH November 2012.

Malaria and malnutrition are common causes of morbidity and mortality in African infants. Data are limited as to whether antimalarial chemoprevention improves nutritional status. We compared the nutritional status of 393 infants living in Tororo, Uganda and randomized to 4 antimalarial chemoprevention arms at 6 months of age; no therapy, monthly sulfadoxine-pyrimethamine (SP), daily trimethoprim-sulfamethoxazole (TS) or monthly dihydroartemisinin-piperaquine (DP). Anthropomorphic measures were made monthly and the primary outcomes of interest were a drop of > 1 standard deviation (SD) in the height-for-age (HAZ) and weigh-for-age (WAZ) z-scores from 6 to 18 months of age. Covariates of interest included breastfeeding status, maternal age, household wealth and chemoprevention arm. Associations between worsening nutritional status and covariates of interest were estimated using multivariate logistic regression. Mean baseline HAZ and WAZ scores were -0.98 and -0.42, respectively. From 6 to 18 months of age, 45% and 23% of infants had a drop of > 1 SD in their HAZ and WAZ scores, respectively. Continued breastfeeding at 18 months was protective against a > 1 SD drop in the HAZ (OR=0.53, p=0.04) and WAZ (OR=0.18, p<0.001) score. Compared to a maternal age of over 25 years, a maternal age of 18 years or younger was protective against a > 1 SD drop in the HAZ (OR=0.30, p=0.001) and WAZ (OR=0.36, p=0.03) score. There were no significant associations between household wealth or chemoprevention and worsening nutritional status and with the exception of a trend towards a lower odds of a > 1 SD drop in the WAZ score (OR=0.46, p=0.06) among infants randomized to monthly SP compared to those randomized to no therapy. In this cohort of infants living in a rural area of Uganda with high malaria transmission intensity, chemoprevention did not clearly improve nutritional status but sustained breastfeeding and younger maternal age were protective against worsening nutritional status from 6 to 18 months of age. Results will be updated when all infants have reached 24 months of age.


Bigira V, Kapisi J, Kinara S, Mwangwa F, Osterbauer B, Okiring J, Kamya MR, Dorsey G. Assessing the association between malaria chemoprevention and the nutritional status of a cohort of young African children.

 

Abstract accepted to ASTMH November 2012.

The burden of malaria remains high for infants in some parts of Africa despite the use of insecticide treated bednets (ITNs). Chemopreventive offers a potential means of reducing the malaria burden in infants, however, optimal drug and dosing strategies are unclear in areas were transmission occurs throughout the year and antifolate resistance is high. A cohort of infants aged 4-5 months were enrolled using convenience sampling in Tororo, Uganda, a rural area with perennial high transmission intensity. Infants received an ITN at enrollment and were followed for all their health care needs 7 d/wk. At 6 months of age, infants were randomized using an open label study design to one of four treatment arms; no therapy, monthly sulfadoxine-pyrimethamine (SP), daily trimethoprim-sulfamethoxazole (TS), or monthly dihydroartemisinin-piperaquine (DP). Study drugs were self-administered at home and continued until the infants reach 24 months of age. The primary end point was the incidence of malaria using passive surveillance between 6-24 months of age or early study termination. Malaria incidence was compared using a negative binomial regression model with measures of association expressed as the protective efficacy (PE=1-incidence rate ratio). Preliminary results are presented here. Of 400 infants enrolled, 393 were randomized to therapy of which; 38 were withdrawn before 24 months of age, 277 are actively being followed and 78 have reached 24 months of age. The incidence of malaria is 5.69 episodes per person year (PPY) among those randomized to no therapy; 5.47 episodes PPY among those randomized to monthly SP (PE=7%, 95% CI -17-26%); 4.32 episodes PPY among those randomized to daily TS (PE=26%, 95% CI 7-42%); and 2.32 episodes PPY among those randomized to monthly DP (PE=60%, 95% CI 48-68%). Preliminary results suggest that monthly SP is not effective at preventing malaria, daily TS is associated with only modest protective efficacy, and monthly DP is the most effective regimen. Final results will be available after Sept. 2012 when all infants reach 24 months of age.

 

Asadu Sserwanga, Ruth Kigozi, Anne Gasasira, Sussann Nasr, Melody Miles, Denis Rubhahika, Sarah Staedke, Moses Kamya, Grant Dorsey, Arthur Mpimbaza. ANTIMALARIAL PRESCRIPTION PRACTICES IN THREE PUBLIC HOSPITALS LOCATED IN AREAS OF VARYING ENDEMICITY IN UGANDA.

 

In Uganda antimalarials are often prescribed when malaria is unlikely, a problem that is becoming critical following the adaptation of effective but expensive ACTs as the 1st line treatment for uncomplicated malaria. Less known is the extent of irrational use of anti-malarials among hospitalized patients. We present data on anti-malarial prescription practices among hospitalized children with microscopy results. As part of an inpatient malaria surveillance program data was collected from three public hospitals in Uganda: Tororo (high transmission), Jinja (medium transmission) and Kambuga (low transmission). At each site, a standardized case record form was used to collect individual patient level data, including medicines prescribed during hospitalization. Between Jan to Dec11, 15748 children were hospitalized in all three hospitals; Tororo (4949), Jinja (9202) and Kambuga (1597). Over 97% of patients had a thick blood smear performed. Proportion of hospitalized children with a positive blood smear was 60% in Tororo, 47% in Jinja and 34% in Kambuga. Of children with negative blood smear, 280 (14%) in Tororo,
3003 (63%) in Jinja and 683 (66%) were prescribed an antimalarial. Quinine was the most commonly prescribed anti-malarial among children with positive (94%) and negative (84%) test results. Among children prescribed an anti-malarial, the unadjusted odds of death was higher among those with negativeresults as compare to those with positiveresults (OR1.65 95%CI 1.25-2.17, P <0.001). When underlying diagnosis, severity of illness, age and antibiotic use were adjusted for in logistic regression
no significant difference in the odds of death was noted between the two groups. Much as there has been improvement in the proportion of children tested for malaria at the sites, prescription of anti-malarials to
patients with negative malaria test results remains unacceptably high at two of the sites. With no clear benefit of this practice there is an urgent need to better understand reasons why clinicians continue to treat
patients for malaria even when test results are negative.

 

Veronica Ades, Emmanuel Arinaitwe, Boaz Ninsiima, Olive Muggaga, Andrew Walakira, Teja Patil, Moses R. Kamya, Sussann Nasr, Scott Filler, Grant Dorsey. ASSOCIATIONS BETWEEN FIVE DIAGNOSTIC METHODS OF PLACENTAL MALARIA AND LOW BIRTH WEIGHT IN AN AREA OF HIGH MALARIA TRANSMISSION IN TORORO, UGANDA.

 

The adverse consequences of placental malaria (PM) have been well established. Most studies rely on measures of PM as a surrogate marker of adverse birth outcomes such as low birth weight (LBW). However, there are no consistent standards for defining PM. Determination of a diagnostic standard is essential in order to compare studies using PM as the outcome of interest. This study compared the associations between 5 different definitions of PM and LBW. A total of 565 HIV-uninfected pregnant women were enrolled at delivery and infants were weighed at birth. LBW was defined as less than 2500 grams. Specimens collected included placental blood and tissue for histopathology. Placental blood was used for 3 definitions of PM: 1) positive blood smear (BS) for asexual parasites, 2) positive HRP2-based rapid diagnostic test (RDT), and 3) positive PCR. Placental histopathology was used for 2 definitions of PM: 1) any evidence of asexual parasites or hemozoin pigment, and 2) a quantitative assessment of hemozoin pigment (present in > 50% of 50 high powered fields examined.) The overall prevalence of PM defined by placental BS, placental RDT, placental blood PCR, conventional histopathology, and quantitative assessment of hemozoin pigment was 17.5%, 23.4%, 28.1%, 65.8% and 16.9%, respectively. Placental BS and RDT were significantly associated with LBW (RR=1.72, CI=0.99-2.99 and RR=1.97, CI=1.19-3.26, respectively) whereas placental PCR was not (RR=1.42, CI=0.72-4.18). Any evidence of PM by histopathology was not significantly associated with LBW (RR=1.73, CI=0.72-4.18); however, the
quantitative assessment of hemozoin pigment was strongly associated with LBW (RR=3.60, CI=1.75-7.39). Placental histopathology was the most sensitive test for evidence of active or past placental malaria. Placental  BS and RDT were also associated with LBW, while placental PCR was not. A definition of PM based on quantitative measure of hemozoin pigmentfrom histopathology specimens may provide the best surrogate measure of adverse birth outcomes.

 

Emmanuel Arinaitwe, Veronica Ades, Boaz Ninsiima, AndrewWalakira, Olive Muggaga, Teja S. Patil, Moses R. Kamya, SussanNasr, Scott Filler, Grant Dorsey. ASSOCIATIONS BETWEEN INTERMITTENT PREVENTIVE THERAPY WITH SULFADOXINE-PYRIMETHAMINE AND
PLACENTAL MALARIA IN AN AREA OF HIGH ANTIFOLATE RESISTANCE IN TORORO, UGANDA.

 

Intermittent preventive treatment with sulfadoxine-pyrimethamine during pregnancy (IPTp-SP) is widely recommended in sub-SaharanAfrica to reduce the risk of placental malaria (PM) and the adverse birth
outcomes associated with this disease. However, there are reports thatthe efficacy of IPTp-SP is waning, especially in parts of East Africa whereantimalarial resistance to antifolate drugs has become widespread.
We conducted a cross-sectional study of 565 HIV uninfected womengiving birth at Tororo District Hospital, an area of Eastern Uganda withhigh transmission intensity. The primary objective of the study was tomeasure the association between reported use of SP during pregnancy(from antenatal cards) and the risk of PM defined as any presence ofasexual parasites or hemozoin pigment using placental histopathology. The proportion of women who reported taking 0, 1, 2 and 3 doses of SP during pregnancy was 6%, 36%, 57% and 2% women, respectively. The prevalence of placental malaria was 74% among women who reported taking 0-1 doses of SP and 60% among women who reported taking 2-3 doses of SP. Using multivariate logistic regression, women who reported taking 2-3 doses of SP had a lower odds of PM (OR=0.55, 95% CI 0.32- 0.96, p=0.04) compared to those who reported taking 0-1 dose of SP.
Compared to multigravida women, those who were secundagravida (OR=3.11, p=0.001) or primagravida (OR=6.13, p<0.001) had a higher odds of PM. Reported use of insecticide treated bed nets was associated
with a lower odds of PM (OR=0.57, p=0.05) and women from households with a wealth index below the median had a higher odds of PM (OR=3.30, p<0.001). There was no association between the woman’s education level and the odds of PM. The prevalence of placental malaria by histopathology was very high in an area of Uganda with high transmission intensity. The reported use of 2-3 doses of SP was associated with modest protection against PM despite widespread antifolte resistance which has been previously reported from this area.

 

Danica A. Helb, Philip L. Felgner, Peter D. Crompton, Li Liang, Boubacar Traore, Emmanuel Arinatwe, Harriet Mayanja, Philip J. Rosenthal, Moses R. Kamya, Grant Dorsey, Chris J. Drakeley, Bryan Greenhouse. DEVELOPING NOVEL SEROLOGIC ASSAYS OF MALARIA EXPOSURE AND PROTECTION.

 

Current methods for assessing Plasmodium falciparum (Pf) transmission intensity are labor intensive and inaccurate, limiting our ability to assess effects of control interventions. In particular, there are no standard biomarkers to assess exposure or immunity to malaria parasites. Antibody
responses to Pf develop as a function of the number and timing of Pf exposures. Kinetics of antibody responses to specific Pf antigens have only been evaluated for a small subset of antigens, but have been shown to differ. Specific antibody responses are known to provide protection from malaria, but protective responses are poorly defined. We propose that assessment of antibody responses to appropriately selected Pf antigens will allow estimation of recent and cumulative exposure to Pf and estimation of protection from malaria. Previously, we probed a microarray containing ~23% of the Pf proteome with plasma from 220 subjects in Mali and identified serologic responses to 49 Pf proteins associated with protection. Here, we analyzed these microarray data to identify novel markers of  prior exposure and additional biomarkers of protection to Pf. 47 antigens were identified as candidate markers for cumulative exposure by selecting
responses with the best linear fit of increased antibody intensity with increasing age in children 2-10 years. 78 candidates for recent exposure were identified as responses with either the most significant difference in reactivity between the beginning and end of the malaria transmission season or the best ability to predict elapsed time since last parasitemia, assuming an exponential decay of antibodies. 49 additional candidates for protection were identified by variable importance indices in random forest analysis. Based on these analyses, an array with 185 unique proteins will be tested with longitudinal samples from Ugandan children in a wide variety of transmission settings in an attempt to translate estimates of Pf exposure and protection at an individual level to estimates of transmission intensity and immunity at a population level.

 

Arthur Mpimbaza, Anne Gasasira, Asadu Sserwanga, Ruth Kigozi, Stella Kakeeto, Humphrey Wanzira, Fred Kizito, Denis Rubahika, Sussann Nasr, Melody Miles, Steven S. Yoon, Michelle Chang, Sarah G. Staedke, Moses Kamya, Grant Dorsey. ESTIMATES OF MALARIA MORBIDITY BEFORE AND AFTER THE IMPLEMENTATION OF A SENTINEL SITE INPATIENT MALARIA SURVEILLANCE SYSTEM IN UGANDA.

 

In Uganda, the National Malaria Control Program (NMCP) relies on Health Management Information System (HMIS) data for planning and monitoring trends in malaria burden yet majority of malaria cases
reported are based on clinical case definition. For the past 2 years, we have implemented an in-patient malaria sentinel surveillance program at select district hospitals with emphasis on laboratory-based case definition. To better characterize the quality of HMIS-based malaria data, and understand the true burden of malaria in Uganda, we compare HMIS data to malaria sentinel surveillance site data at four public hospitals. These hospitals are situated in districts with varying malaria endemicity: Tororo and Apac (high transmission), Mubende (medium transmission) and Kambuga (low transmission). At the four sentinel hospitals, >95% of inpatient children less than 5 years were tested for malaria, and only those children with positive laboratory confirmation were recorded as malaria cases. Based on HMIS data, the proportion of hospitalized children under 5 with malaria was higher 12 months prior to start of the program as compared to 12 months after: Tororo (94% vs. 85%), Kambuga (83% vs. 52%), Mubende (71% vs. 55%) and Apac (67% vs. 40%). Actual comparison of HMIS data to surveillance program data, 12 month after its start, showed that HMIS data overestimates the burden of malaria when compared to surveillance program data: 27 percent higher in Kambuga (25% vs. 52%), 24 percent higher in Tororo, (61% vs. 85%), 18 percent higher in Mubende (55% vs. 37%) and 7 percentage points higher in Apac (42% vs. 35%). Improved precision of HMIS estimates of malaria adopted after start of the program may have contributed, in addition to other factors, to the observed differences in disease burden determined
by HMIS before and after the start of the program. Even then, HMIS overestimated the burden of malaria among hospitalized children after start of the program. In order to improve the quality of HMIS malaria data, a case definition based on laboratory confirmation should be adopted.

 

Christian Nsanzabana, Philip J. Rosenthal. SELECTION OF PLASMODIUM FALCIPARUM STRAINS WITH REDUCED SENSITIVITY TO THE HIV PROTEASE INHIBITOR LOPINAVIR

 

Some HIV protease inhibitors (PIs) are active against cultured malaria parasites at concentrations that are clinically relevant. Lopinavir acted against multiple laboratory strains of Plasmodium falciparum with an IC50 of 1-3μM, and against two freshly cloned strains from Tororo, Uganda with IC50 of 1.7μM. With standard dosing of lopinavir/ritonavir, lopinavir circulates at ~9-19 μM. Importantly, in an ongoing clinical trial, children treated for HIV infection with a lopinavir-ritonavir-based antiretroviral regimen experienced a 41% decrease in the incidence of malaria compared to children treated with a non-nucleoside reverse transcriptasebased regimen. Impacts of the PI on malaria were likely due principally to
pharmacokinetic interactions between ritonavir and lumefantrine, but also the direct antimalarial activity of lopinavir. The antimalarial mechanism of action of HIV PIs is uncertain, although it is likely that they act against one or more of the ten plasmodial aspartic proteases known as plasmepsins.
To help to characterize mechanisms of action and resistance, we selected malaria parasites with decreased sensitivity to lopinavir. We cultured the P. falciparum multidrug resistant reference strain W2 and the sensitive strain 3D7 with selective concentrations of lopinavir for fourteen months.
Changes in sensitivity were selected only very slowly. The strains obtained after culture for 212 cycles under lopinavir pressure had IC50s of ~10μM for both strains, corresponding to three times the IC50 of the parental strains. We are currently cloning parasites with reduced sensitivity to lopinavir and assessing the stability of the phenotype when drug pressure is removed. Differences between parasites with varied sensitivity will be assessed, including sequencing of plasmepsin genes. Our goal is to determine if alterations in lopinavir sensitivity selected in culture are due to specific genetic changes in plasmepsin genes or other portions of the P. falciparum genome. If alterations mediating changes in lopinavir sensitivity are identified, surveillance for these genetic determinants may help to guide optimal antiretroviral therapy in HIV-infected children at risk of malaria.

 

Patrick K. Tumwebaze, Jessica Bloome, Oswald Byaruhanga, Christine Nakazibwe, Andrew Walakira, Jaffer Okiring, Samuel L. Nsobya, Roland A. Cooper, Philip J. Rosenthal. ARTEMETHER-LUMEFANTRINE SELECTS FOR MALARIA PARASITES WITH DECREASED LUMEFANTRINE SENSITIVITY ALTHOUGH PARASITES REMAIN SENSITIVE TO THIS REGIMEN IN TORORO, UGANDA.

 

Artemisinin-based combination therapies (ACTs) may select for malaria parasites with decreased drug sensitivity. We studied the sensitivity of parasites from children enrolled in treatment and prevention trials in Tororo, Uganda from June, 2010 to February, 2012. When Plasmodium falciparum malaria was diagnosed, blood was obtained, parasites (286 isolates) were cultured with serial dilutions of chloroquine (CQ), monodesethylamodiaquine (AQ), quinine (QN), dihydroartemisinin (DHA), lumefantrine (LM), or piperaquine (PQ) for 72 h, and ex vivo sensitivities were assessed by HRP-2-based ELISA. Sensitivities (nM) to CQ (median IC50 486.2; IQR 206.5-748.8), AQ (83.3; 58.4-132.4), PQ (20.3; 7.6-47.5) and QN (126.4; 74.9-196.3) varied widely; parasites were highly sensitive to LM (2.7; 0.97-6.7) and DHA (1.7; 1.0-2.8). IC50 values for 4 successive quartiles, each with 71-73 isolates collected over ~4 months, varied
little for control strains (3D7 IC50s 0.54-1.8 nM) and all drugs except LM and PQ. For PQ, sensitivity decreased after the first quartile (median IC50 6.5), but was then stable (26.6-32.0). For LM, IC50s were low, but increased consistently (successive quartiles 1.1, 2.3, 3.5, and 6.2, p<0.05 for all comparisons except 2nd-3rd quartiles). Receiving monthly DHAPQ in a prevention trial was not associated with changes in PQ sensitivity compared to those receiving placebo. Having received artemether-LM (AL)
within 60 days as treatment for a prior episode of malaria was associated with decreased sensitivity to LM (median IC50 1.59 for those without [n=84] vs. 3.24 for those with [n=119] recent AL; p=0.022 [GEE regression with log IC50 values]), but no significant change in sensitivity to the other study drugs. In summary, recent isolates of P. falciparum in Tororo were highly sensitive to components of AL, the national treatment regimen, but treatment with AL selected for parasites with decreased sensitivity, and
overall sensitivities decreased from 2010 to 2012. Longitudinal surveillance of sensitivities of parasites under different selective drug pressures continues.

2011, PHILIDELPHIA, PA, USA

Achan J, Ruel T, Kakuru A, Ikilezi G, Clark TD, Charlebois E, Rosenthal PJ, Dorsey G, Havlir DV, Kamya MR. Significant Reduction in Risk of Malaria among HIV-Infected Children Receiving LPV/r-Based ART Compared to NNRTI-Based ART: A Randomized Open Label Trial. Abstract presented at ASTMH, Philadelphia Dec 2011
HIV-infected children living in sub-Saharan Africa continue to suffer high morbidity and mortality from malaria, requiring additional control measures. HIV protease inhibitors have some activity against P.falciparum in vitro. We evaluated the efficacy of PI-based vs. NNRTI-based ART regimens for malaria risk reduction in HIV-infected children. This was a randomized open label trial in Tororo, Uganda. Participants were HIV- infected children aged 2 months to 5 years eligible for antiretroviral therapy (ART) or currently receiving non-nucleoside reverse transcriptase inhibitor (NNRTI) based ART with virological suppression (HIV RNA<400 copies/ml). Participants received either PI-based (LPV/r) ART or NNRTI-based ART and were followed up for 2 years. Using intent-to-treat analysis, we compared the incidence-density of malaria between the study arms using Poisson regression. Between September 2009 and July 2011, we enrolled 176 children, 89 received NNRTI-based ART and 87 PI-based ART. Malaria incidence was significantly higher in the NNRTI arm compared to the PI arm, 2.25 vs. 1.32 episodes/person year, IRR 0.59, 95% CI 0.36-0.97, p=0.037. Adequate clinical and parasitological response rates after treatment with artemether-lumefantrine were 86.0% (92/107) in the PI arm vs. 57.2% (99/174) in the NNRTI arm, p< 0.0001. The cumulative 28-day risk of treatment failure unadjusted by genotyping was significantly higher in the NNRTI arm compared to the PI arm; 41.1% vs. 14.0%; HR 0.31, p= 0.004. Median serum lumefantrine levels were significantly higher in the PI arm compared to the NNRTI arm on follow-up days 3, 7 and 14. In the PI arm, day 7 lumefantrine levels > 300ng/ml were associated with a > 85% reduction in the risk of recurrent malaria after 63 days. Use of PIs was associated with a significant reduction in the incidence of malaria and the risk of recurrence which may be explained by pharmacokinetic interactions and potential synergy between PIs and lumefantrine. PI-based ART could be considered as one of the strategies for malaria prevention in HIV-infected children.


Tumwebaze PK, Byaruhanga O, Okiring J, Nsobya SL, Cooper RA, Rosenthal PJ. Ex vivo drug sensitivity of malaria parasites under selective pressure in Tororo, Uganda.

 

Abstract presented at ASTMH, Philadelphia Dec 2011
Artemisinin-based combination therapies (ACTs) are standard treatments for uncomplicated malaria in Africa. ACTs provide highly effective treatment, and regular use may offer protection against malaria in high risk populations. However, increased use of ACTs may select for parasites with decreased sensitivity. We studied the ex vivo sensitivity of malaria parasites collected from children enrolled in treatment and prevention trials in Tororo, Uganda from June, 2010 to August, 2011. When P. falciparum malaria was diagnosed, blood was obtained, parasites were cultured with serial dilutions of chloroquine (CQ), monodesethylamodiaquine (AQ), quinine (QN), dihydroartemisinin (DHA), lumefantrine (LM), and piperaquine (PQ) for 72 hours, and the ex vivo activity of antimalarial drugs was assessed by HRP-2-based ELISA. Preliminary findings based on evaluations of 153 isolates are presented here. Sensitivities to CQ (median IC50 283 nM; IQR 99.0-585), AQ (83.8 nM; 45.6-140), and QN (73.4 nM; 41.6-113) varied widely. Parasites were generally highly sensitive to LM (1.3 nM; 0.7-3.1) and DHA (1.7 nM; 0.9-3.0), but sensitivities to PQ varied over a fairly wide range (9.2 nM; 4.0-31.5). Considering results longitudinally, IC50 values for 4 successive intervals, each containing 38-39 isolates, varied little for control parasite strains and all drugs except LM and PQ, which each showed a trend toward increasing IC50 over time. However, considering drug exposure, neither receiving monthly DHA-PQ nor having received artemether-LM (AL) as treatment for a prior episode of malaria within 60 days was associated with decreased sensitivity to the relevant drugs. In summary, recent isolates of P. falciparum in Tororo had varied sensitivity to CQ, AQ and QN and remained highly sensitive to components of AL and DHA-PQ, the current national treatment regimens. However, although parasites were generally highly sensitive to LM and PQ, sensitivities may be decreasing. Longitudinal surveillance of ex vivo sensitivities of isolates under different clinical selective pressures continues.


Nsanzabana C, Rosenthal PJ. In vitro activity of antiretroviral drugs against Plasmodium falciparum.

 

Abstract presented at ASTMH, Philadelphia Dec 2011
We tested the in vitro activity of 19 antiretroviral drugs against the W2 and 3D7 strains of Plasmodium falciparum at concentrations up to 50 μM. None of 5 tested nucleoside reverse transcriptase inhibitors demonstrated activity. Two non-nucleoside reverse transcriptase inhibitors, efavirenz and etravirine were active; nevirapine was not active. Also active were the fusion inhibitor enfuvirtide and entry inhibitor maraviroc. The integrase inhibitor raltegravir was not active. However, for all active drugs mentioned above, IC50s were considerably greater than concentrations achieved with standard dosing. The effects most likely to be clinically relevant were with HIV protease inhibitors. Of tested compounds, activity was seen with lopinavir, atazanavir, saquinavir, nelfinavir, ritonavir, tipranavir, and amprenavir, but not darunavir. Lopinavir was active at levels well below those achieved with standard dosing of co-formulated lopinavir-ritonavir. Lopinavir also demonstrated modest synergy with the antimalarial lumefantrine (mean FIC index 0.66 for W2 and 0.53 for 3D7). Prior data showed that lopinavir-ritonavir also extends the pharmacokinetic exposure of lumefantrine. Thus, when used to treat HIV infection, lopinavir-ritonavir may have clinically relevant antimalarial activity and also enhance the activity of antimalarials.


Abel Kakuru, Prasanna Jagannathan, Humphrey Wanzira, Emmanuel Arinaitwe, Victor Bigira, Jaco Homsy, Moses Kamya, Jordan Tappero, Mary Muhindo K, Emmanuel Osilo, Anne Gasasira, Grant Dorsey. Effect of daily trimethoprim-sulfamethoxazole prophylaxis on the risk of gametocytemia in Ugandan children. Abstract presented at ASTMH, Philadelphia 2011.


Antimalarial treatment with sulfadoxine-pyrimethamine is associated with an increase in the density of gametocytes, the transmissible stage of malaria. Daily co-trimoxazole (CTX) prophylaxis has been shown to reduce the incidence of malaria; however data on its effect on the risk gametocyteamia is limited. We evaluated the effect of daily cotrimoxazole on the risk of gametocytaemia in Ugandan children. We enrolled 100 HIV–unexposed, 203 HIV exposed and 48 HIV infected children between the ages of 6 weeks and 9 months. CTX prophylaxis was prescribed every month for all HIV infected during follow-up and for HIV-exposed children during breastfeeding. HIV –unexposed children were not taking CTX prophylaxis. After ceasing to breastfeed, HIV exposed children were tested for HIV using DNA-PCR. Children who tested HIV negative were randomized to stop or continue CTX prophylaxis. Children who were randomized to continue CTX prophylaxis were later re-randomized to continue or stop upon becoming 2 years of age. All children were followed-up in a study clinic for all their medical care. Gametocytes were diagnosed from thick blood smears using microscopy and reported as present or absent. We compared the monthly risk of gametocytaemia in children taking CTX prophylaxis to those not taking CTX prophylaxis, stratified by visit type, using binomial generalized estimating equations with robust standard errors and adjusting for residence, age, and assigned antimalarial treatment group. There were 5273 months of observation where CTX was not prescribed compared to 4203 months where CTX was prescribed. For all visits the proportion of smears with gametocytes was 4.4%. In blood smears done on the day of diagnosis of malaria and during malaria follow-up, CTX was associated with a 74% increase in the risk of gametocytaemia (RR=1.74, P=0.004 and RR=1.74, P=0.001 respectively). Gametocytaemia was rare in our cohort. Daily CTX prophylaxis was associated with an increased risk of gametocytaemia suggesting a potential of increasing malaria transmission.

 

Laura Steinhard, Adoke Yeka, Sussann Nasr, Denis Rubahik, Asadu Sserwanga, Humphrey  Wanzira, Geoff Lavoy, Moses Kamya, Grant Dorsey, Scott Filler. DISTRICT-BASED HOUSEHOLD SURVEY DATA AND ASSOCIATED BIOMARKERS IN INDOOR RESIDUAL SPRAYING (IRS) AND NON-IRS DISTRICTS IN NORTHERN UGANDA.


Indoor residual spraying (IRS) with insecticides is a primary intervention to reduce malaria transmission. In highly malaria-endemic Northern Uganda, selected districts have been sprayed since 2007 with DDT and pyrethroids, before localized political opposition to DDT and documented resistance to pyrethroids prompted a shift to carbamates in 2010. Data from a household survey and associated biomarker collection in late 2010 in three contiguous districts of Northern Uganda were used to compare one non-sprayed district (Lira) with two IRS districts (Apac, sprayed once with carbamates in 2010 after one round each of DDT (2008) and pyrethroids (early 2010) and Pader, which received two rounds of carbamate spraying in 2010, following four rounds of pyrethroids (2007-2009)). District level anemia and parasitemia prevalence estimates from a total of 1,773 children less than five years of age were calculated from the two-stage, cluster sample survey, using sampling weights and accounting for clustering. Parasitemia levels were significantly lower in both IRS districts compared to the non-sprayed district. In Apac, 37.2% of children had positive malaria blood smears, compared to 50.1% of children in nonsprayed
Lira district, p<0.01. Parasitemia prevalence was lowest in Pader (16.9%, p<0.001 compared to both Apac and Lira), which had been sprayed twice with carbamates in 2010. Anemia (hemoglobin<11g/dL)
was less common in Apac (38.4%) and Pader (36.9%), compared to Lira (53.0%), p<0.001. Bednet use by children was significantly higher in the IRS districts (69.6% in Apac and 64.6% in Pader) than in Lira (49.5%), but there were no significant differences between the districts in terms of food security or distance to the nearest health facility. These results indicate lower malaria burdens, according to biomarkers, in IRS districts compared to non-sprayed districts in Northern Uganda. Additional research is
needed to better define causal relationships between IRS schedules and formulations and reductions in malaria indicators in areas of high transmission intensity.

 

Darren J. Creek, Li Yan, Wendy J. Verret, Victor Bigira, Emmanuel Arinaitwe, Humphrey Wanzira, Abel Kakuru, Niklas Lindegardh, Joel Tarning, Taylor G. Sandison, Francois Nosten, Grant Dorsey, Nancy Sambol, Sunil Parikh, Francesca T. Aweeka. PHARMACOKINETIC PREDICTORS OF TREATMENT OUTCOME FOR DIHYDROARTEMISININ-PIPERAQUINE IN UGANDAN INFANTS WITH UNCOMPLICATED MALARIA.

 

Abstract presented at ASTMH, Philadelphia 2011. 

Dihydroartemisinin-piperaquine (DP) is the most recently adopted 1st line artemisinin-combination therapy (ACT) option for the treatment of malaria. We evaluated the pharmacokinetics (PK) and pharmacodynamics (PD) of piperaquine (PQ) in 107 infants, aged 6 to 24 months, within the context of a longitudinal study in the high transmission area of Tororo, Uganda. Capillary plasma samples were collected prior to the 1st dose of DP, and at variable times up to day 28 after each treatment for P. falciparum malaria. Children were followed longitudinally, and underwent sampling for all episodes of malaria. 218 episodes of malaria (1314 samples) occurred over the 7 month study period. Median day
7 concentrations were 41.9 ng/ml (IQR, 30.2, 56.6), Univariate and multivariate analyses revealed that day 14, 21, and 28 levels were significantly associated with the risk of recurrent malaria on day 42. The
risk of recurrent infection increased 85% per log10 increase in PQ level on day 14. Those individuals with a PQ level in the lowest quartile (<10.5 ng/ ml) on day 28 had a 41% risk of failure, while those above that threshold had a 20% cumulative risk of failure at 42 days (p=0.01). Notably, out of 132 children who had a prior episode of malaria treated with DP, 119 had detectable PQ at the time of diagnosis of their next episode of malaria (constituting a period of up to 4 months), with concentrations ranging from 1.5 to 41.9 ng/mL. Population PK analysis was also performed. A three compartment PK model with first order absorption of drug and age-dependent apparent clearance best described PQ disposition in infants. Additional population PK/PD analyses will be presented. Our study provides the 1st data on the disposition of PQ in children < 2 yrs of age. PQ exposure on day 7 for infants is lower than day 7 levels previously reported in older children and adults. Moreover, PK exposure correlates strongly with clinical outcomes. In addition, PQ appears to remain detectable for extended periods, and was detectable in the majority of infants upon recurrent infection.

 

Sanjiv M. Baxi, Anne Gasasira, Ruth Kigozi, Asadu Sserwanga, Stella Kakeeto, Sussann Nasr, Moses R. Kamya, Scott Filler, Grant Dorsey. EFFECT OF INDOOR RESIDUAL SPRAYING OF INSECTICIDESON THE MALARIA SLIDE POSITIVITY RATE IN AN AREA OF HIGH TRANSMISSION INTENSITY IN UGANDA.

 

Abstract presented at ASTMH, Philadelphia 2011. 

There is limited data on the effectiveness of indoor residual spraying (IRS) of insecticide on malaria morbidity in areas of high malaria transmission intensity in Africa. Uganda has recently implemented an IRS program in areas of high transmission intensity through support from the U.S. President’s Malaria Initiative. We sought to evaluate the temporal relationship between IRS and the slide positivity rate (SPR) among patients with suspected malaria at one sentinel health facility between Nov. 2006 and Feb. 2011 in the Apac District of Uganda, where the entomological inoculation rate was estimated to be 1586 in 2001. During this period, 3 rounds of IRS were completed. Round 1: March-May 2008 with dichlorodiphenyltrichloroethane (DDT); Round 2: March-April 2010 with alpha-cypermethrin; Round 3: August 2010 with the carbamate Bendiocarb. Over the 52 month observation period a total of 83,829
patients were seen, 41,294 (49%) had suspected malaria, and 77% of those with suspected malaria underwent microscopy. Associations between 6 month periods (with the exception of only 4 months between the 2nd and 3rd rounds) related to IRS and relative changes in the SPR were estimated using Poisson regression after controlling for age and seasonality. The SPR was 45% during the 6 months prior to completion of the 1st round of IRS. The 6 months following completion of the 1st round was associated with a 7% relative reduction in the SPR (p=0.22) compared to the 6 months before completion of the 1st round. The 4 months following completion of the 2nd round was associated with a 12% relative reduction in the SPR (p=0.01) compared to the 6 months before completion of the 2nd round. The 6 months following completion of the 3rd round was associated with a 27% relative reduction in the SPR  (p<0.001) compared to the 4 months before completion of the 3rd round. In this area of very high transmission intensity, the 2nd and 3rd rounds of IRS were associated with a significant decrease in the SPR. Our analysis will be updated following completion of the 4th and 5th rounds of IRS in 2011.

 

Emmanuel Arinaitwe, Anne Gasasira, Wendy Verret, Jaco Homsy, Humphrey Wanzira, Abel Kakuru, Taylor G. Sandison, Jordan W. Tappero, Moses R. Kamya, Grant Dorsey. THE ASSOCIATION BETWEEN MALNUTRITION AND THE RISK OF MALARIA IN A COHORT OF HIV-INFECTED AND UNINFECTED UGANDAN YOUNG CHILDREN.

 

Abstract presented at ASTMH, Philadelphia 2011. 

In sub-Saharan Africa, malaria, malnutrition and HIV infection remainmajor causes of morbidity and mortality in children under five years of age.Few studies have investigated the relationships across malnutrition, malariaand HIV in this age group. Moreover, there is conflicting data on whetheror not malnutrition is a risk factor for malaria, and how HIV may modifythe malaria-malnutrition relationship. From August 2007 to January 2008,we recruited a cohort of 100 HIV-unexposed, 203 HIV-exposed (born toHIV-infected mothers) and 48 HIV-infected children 6 weeks to 1 year ofage living in a high malaria transmission area in rural Uganda. Childrenwere followed up until 2.5 years of age and seen for all their medicalconditions in the study clinic. All children were provided with insecticidetreatedbed nets. Daily trimethoprim-sulfamethoxazole (TS) prophylaxiswas prescribed for HIV-exposed breastfeeding, and HIV-infected children.Height and weight were measured at every visit and stunting was definedas height-for-age z score < -2. Malaria was diagnosed when a childpresented with fever and a positive blood smear. The incidence of malariawas compared using negative binomial regression controlling for potentialconfounders with the measure of association expressed as incidence rateratio (IRR). The overall incidence of malaria was 3.64 cases per personyear. Stunting was an independent risk factor for malaria (IRR 1.20,95% CI. 1.04-1.39, p=0.01) as was increasing age (IRR=1.41 per 1 year
increase, 95% CI. 1.10-1.81, p=0.01), while Urban vs. rural residence wasassociated with a decreased risk of malaria (IRR=0.42, 95% CI. 0.34-0.52,p<0.001). There was no association between HIV infection and malaria(IRR=0.86, 95% CI. 0.65-1.15, p=0.31), but HIV-infected children weremore likely to be stunted (RR=1.50, 95% CI.1.31-1.72, p<0.001. Thisstudy suggests that stunting may be associated with an increased risk ofmalaria regardless of child’s HIV-status.

2010, ATLANTA, GA, USA

 

Ruth K. Nassali, Hasifa Bukirwa, Stella Kakeeto, Fred Kizito, Asadu Sserwanga, Grant Dorsey, Moses Kamya, Ann Gasasira. THE EFFECT OF CHANGES IN RAINFALL ON THE BURDEN OFMALARIA IN AREAS OF HIGH AND LOW TRANSMISSIONSETTINGS.

 

Abstract presented at Atlanta ASTMH 2010

The effect of rainfall on malaria risk may vary across differing transmission and environmental settings and further by the level of intervention deployment. Clarifying this relationship may be informative to malaria control programs. The objective of this study was to determine the effects of change in rainfall on the malaria burden in 2 different endemic settings. The Uganda Malaria Surveillance Project collects daily malaria morbidity data from 6 sentinel health facilities around Uganda. In this ongoing study, we utilized malaria data from the lowest and highest transmission sentinel settings: Kamwezi Health Center in Kabale district (EIR < 1) and Aduku Health Centre, in Apac district (EIR = 1564) respectively. Routinely collected daily rainfall data from Kabale and Apac districts were obtained from Uganda’s national meteorological department. We used linear regression models to assess the association between total monthly rainfall and malaria slide positivity rate (SPR) for the next month, adjusting for age and number of malaria laboratory tests done. This preliminary analysis includes data collected over 26 months in Kabale/Kamwezi and 41 months in Apac/Aduku. The median total monthly rainfall in Kabale was 92.7mm (IQR 61-114.6) and 112.3mm (IQR 4.4-202.1) in Aduku. Age-standardized SPRs ranged from 13.4% to 65.6% in Kamwezi (median 29.4%) and from 26.2%% to 57.7% in Aduku (median 46.1%). In Kabale, a 1mm increase in rainfall increased the SPR by 0.002% (p = 0.036). Changes in rainfall were not associated with changes in malaria diagnosed in Apac. These initial findings suggest a modest association between increase in rainfall and subsequent malaria upsurges in areas of low but not high transmission intensity. Data collection on intervention coverage and environmental factors is ongoing.

 

Asadu Sserwanga, Ruth Kigozi, Hasifa Bukirwa, StellaKakeeto, Anne Gasasira, Manoj Menon, Sussann Nasr, ScottFiller, Jamal Harris, Grant Dorsey, Ebony Quinto, Moses Kamya.THE IMPACT OF A SENTINEL SITE MALARIA SURVEILLANCEPROGRAM ON IMPROVING CASE MANAGEMENT INUGANDA.

 

Abstract presented at Atlanta ASTMH 2010

Malaria surveillance is critical for monitoring trends in malaria morbidity and mortality, but can also be used as a tool for improving case management. The WHO now recommends ACTs for the treatment of uncomplicated falciparum malaria along with prompt laboratory confirmation in all patients suspected of malaria before treatment is started. From August 2006 - January 2007 we implemented a sentinel site malaria surveillance system at the outpatient departments of 5 government health centers in Uganda with a 6th site added in September 2008. This system was established by the Uganda Malaria Surveillance Project in collaboration with the Ministry of Health and Health Management Information System. Individual patient data is entered electronically onsite using a standardized case record form and sent monthly to a core facility using cellular technology. Through February 2010, a total of 397,407 patients were seen of which 54% (range 47- 63% at the 6 sites) were suspected of having malaria. We compared data from the first two months of surveillance with data from the most recent two months (Jan-Feb 2010) to evaluate key indicators in malaria case management. The proportion of patients with suspected malaria for whom a laboratory test was done increased from 44% (range 32-64%) to 97% (range 93-99%). The proportion of patients with a laboratory test done who were appropriately prescribed an antimalarial drug (negative test not prescribed an antimalarial, positive test prescribed an antimalarial) increased from 64% (range 51-78%) to 94% (range 87-98%). The proportion of patients with a positive laboratory test who were prescribed an ACT increased from 50% (35-88%) to 74% (35-91%), although these results were highly variable across the sites. The implementation of sentinel site malaria surveillance system in the context of the existing government system was associated with dramatic improvements in utilization of laboratory services and rationale antimalarial treatment decision making. However, further improvement is needed in ACT prescribing practices.

 

Humphrey Wanzira, Taylor Sandison2Abel Kakuru, VictorBigira, Emmanuel Arinaitwe, Jaco Homsy, Jordan W. Tappero,Moses Kamya, Grant Dorsey. ARTEMETHER-LUMEFANTRINE VERSUSDIHYDROARTEMISININ-PIPERAQUINE FOR THE TREATMENTOF UNCOMPLICATED MALARIA: LONGITUDINAL OUTCOMESIN A COHORT OF YOUNG UGANDAN CHILDREN

 

Abstract presented at Atlanta ASTMH 2010

There are limited comparative data on the long term effects of artemisinin combination therapies (ACTs) for the treatment of malaria. In a cohort of young Ugandan children living in a highly endemic area, we previously reported that artemether-lumefantrine (AL) and  dihydroartemisinin piperaquine (DP) were both highly efficacious, but DP was associated with a longer post-treatment prophylactic effect. Here we aimed to compare longitudinal outcomes in this cohort. Children were given a long-lasting insecticide treated bednet (LLITN) at enrollment and followed for all their healthcare needs. 305 children with a median age of 10 months (range 4-40) were randomized to AL (n=155) or DP (n=150) at the time of their first episode of uncomplicated malaria. The same treatment was given for all subsequent episodes of uncomplicated malaria and episodes of complicated malaria were treated with quinine. After randomization, children were followed a median of 22 months and a total of 2,592 treatments for malaria were given. The incidence of malaria following randomization was higher in the AL arm (5.44 episodes PPY) compared to the DP arm (4.74 episodes PPY), although this difference did not reach statistical significance (IRR=1.13, p=0.06). After randomization, only 27 treatments with quinine (1%) were given for complicated malaria (17 with convulsions, 10 with severe anemia). The incidence of complicated malaria was significantly higher in those randomized to AL compared to DP (IRR=4.84, p=0.006). All 6 early treatment failures were due to the development of complicated malaria within 2 days of initiating treatment with AL. There was one death due to malaria in a child randomized to AL. In this cohort of young children living in a highly endemic area the incidence of malaria was very high despite the use of LLITNs.  However, treatment with AL or DP was highly efficacious and the incidence of complicated malaria was relatively low. DP was associated with a trend towards a modest decrease in the incidence of malaria and may lower the risk of complicated malaria compared to AL.

 

Michelle S. Hsiang, Michael Lin, Christian Dokomajilar, Jordan Kemere, Christopher D. Pilcher, Grant Dorsey, Bryan Greenhouse. PCR-BASED POOLING OF DRIED BLOOD SPOTS FORDETECTION OF MALARIA PARASITES: OPTIMIZATION ANDAPPLICATION TO A COHORT OF UGANDAN CHILDREN.

 

Abstract presented at Atlanta ASTMH 2010

Sensitive, high-throughput methods to detect malaria parasites in low transmission settings are needed. PCR-based pooling strategies may offer a solution. We first used laboratory prepared samples to compare 2 DNA extraction and 4 PCR detection methods across a range of pool sizes  and parasite densities. Pooled Chelex extraction of DNA followed by nested PCR of cytochrome b was the optimal strategy, allowing reliable detection of a single low parasitemic sample (100 parasites/μL) in pool sizes up to 50. This PCR-based pooling strategy was then compared with microscopy using 891 dried blood spots from a cohort of 77 Ugandan cildren followed for 2 years in a low endemic urban setting. Among 419 febrile episodes, 35 cases of malaria were detected using the PCR-based pooling strategy and 40 cases using microscopy. All five cases of malaria not detected by PCR were from samples stored >2 years with parasitemia < 6000/μL, highlighting the issue of possible DNA degradation with long term storage of samples. Among 472 samples collected in asymptomatic children as part of routine surveillance, 15 (3.2%) were positive by PCR based pooling compared to 4 (0.8%) by microscopy (p=0.01). Thus, this PCR-based pooling strategy for detection of malaria parasites using dried blood spots offers a sensitive and efficient approach for malaria surveillance in low transmission settings, enabling improved detection of asymptomatic submicroscopic infections and dramatic savings in labor and costs.

 

Chris Keh, Aashish Jha, Bridget Nzarubara, Philip J. Rosenthal,Grant Dorsey, Douglas F. Nixon, Bryan Greenhouse. ASSOCIATION BETWEEN PLASMODIUM FALCIPARUMANTIBODY RESPONSES AND AMODIAQUINE-SULFADOXINEPYRIMETHAMINETREATMENT FAILURE IN KAMPALA, UGANDA

 

Abstract presented at Atlanta ASTMH 2010

Elimination of Plasmodium falciparum after partially effective therapy is influenced by host immunity. We previously showed that responsesto treatment for uncomplicated malaria with amodiaquine-sulfadoxinepyrimethamine (AQ+SP) were associated with surrogates of immunity, including age and proximity to a mosquito breeding site. To further assess associations between immunity and treatment response we studied humoral antimalarial responses in children in Kampala aged 1-10 years who received AQ+SP for treatment of uncomplicated malaria. We measured IgG responses to the following 8 P. falciparum antigens via ELISA in 207 pairs of serum samples collected on the day of therapy (Day 0) and 14 days after treatment (Day 14): circumsporozoite protein (CSP), liver stage antigen 1 (LSA1), apical membrane antigen 1 (AMA1), merozoite surface proteins 1, 2, and 3 (MSP 1, 2, 3), and the R0 and R2 domains of glutamine rich protein (GLURP). Results were standardized against pooled immune serum from adults living in Kampala. Our primary outcome was the genotype-adjusted risk of recrudescence within 63 days. Associations were estimated using generalized estimating equations. Age adjusted IgG responses to AMA1 on Day 0 and Day 14 were significantly higher in those living closer to the breeding site (p<0.02). Overall risk of treatment failure was 12%. After adjusting for age and parasite polymorphisms associated with treatment failure, the risk of failing therapy was significantly lower in those with higher AMA1 responses on Day 0 (OR=0.79 / doubling of titer, p=0.01). IgG responses for the other antigens were not significantly associated with treatment response, however there was a trend for protection with higher Day 0 responses to MSP 2 (OR 0.79, p=0.06) and 3 (OR 0.81, p=0.09). Our findings demonstrate that antibody responses to AMA1 are associated with blood-stage immunity as measured by host clearance of parasites in the setting of partially effective therapy.

 

Abel Kakuru, Humphrey Wanzira, Emmanuel Arinaitwe, VictorBigira, Jaco Homsy, Moses Kamya, Jordan W. Tappero, GrantDorsey, Taylor Sandison. AN EVALUATION OF THE EFFECT OF TRIMETHOPRIMSULFAMETHOXAZOLEPROPHYLAXIS ON GAMETOCYTEMIAAND ASYMPTOMATIC PARASITEMIA IN HIV-EXPOSEDCHILDREN IN RURAL UGANDA.

 

Abstract presented at Atlanta ASTMH 2010

Treatment with sulfadoxine-pyrimethamine (SP), an antifolate antimalarial, has been associated with increased gametocytemia, especially in the presence of antifolate resistance. However, data are limited regarding the effect of trimethoprim-sulfamethoxazole (TS) prophylaxis on gametocytemia. We previously reported that TS prophylaxis has a 40% protective efficacy against malaria among HIV-exposed (HIV-uninfected infants born to HIV-infected mothers) children, but data are lacking concerning the effect of TS on asymptomatic parasitemia (AP). Here, we examine the effects of TS prophylaxis on gametocytemia and AP. In an area of high malaria endemicity and antifolate resistance in rural Uganda, we randomized 185 HIV-exposed infants (median age= 9.6 months), following breastfeeding and a negative HIV PCR test, to discontinue or continue TS prophylaxis through age 2 years. Routine smears were obtained every 30 days, and time-at-risk was divided into calendar months. Gametocytemia and AP were diagnosed by microscopy (and absence of fever for AP). All smears performed within 7 days of a
malaria episode and during malaria follow-up were censored in assessing for prevalence of AP. Among 98 infants randomized to continue TS, there were 28 episodes of gametocytemia over 1,068 months (2.6%), and among 87 infants randomized to stop TS, there were 8 episodes of gametocytemia over 845 months (1.0%) (RR=2.83, p=0.07). Among children taking TS, there were 77 AP episodes over 812 months (9.5%), and among children who discontinued TS, there were 78 AP episodes over 606 months (12.9%) (RR=0.74, p=0.18). Compared to AP in participants not taking TS, AP in children taking TS prophylaxis was less likely to progress to malaria within 7 days (RR=0.41, p=0.001). Though the overall prevalence of gametocytes was low, TS prophylaxis was associated with a trend toward increasing gametocytemia. Compared to children not taking TS, AP episodes among children taking TS prophylaxis were less likely to progress to clinical malaria, indicating that TS may prevent malaria at the erythrocytic stage.

 

Lauren S. Gong, Catherine Maiteki-Sebuguzi, Philip Rosenthal,Bryan Greenhouse. PONTANEOUS CLEARANCE OF PLASMODIUM FALCIPARUMPARASITEMIA WAS MORE COMMON IN UGANDANCHILDREN WITH SICKLE CELL TRAIT THAN IN THOSE WITH NORMAL HEMOGLOBI.

 

Abstract presented at Atlanta ASTMH 2010

The genetic abnormalities glucose-6-phosphate dehydrogenase (G-6-PD) deficiency and sickle cell trait (HbAS) offer protection against falciparum malaria. They may protect through improved immune clearance of parasites, but this hypothesis has not been tested clinically. 601 randomly selected children from Kampala, aged 1-10, were followed for a median of 1.4 years. Blood smears were read every 30 days and any time a child presented with fever or history of fever. Children with malaria, defined as asexual parasites on blood smear and fever, were treated after randomization to one of 3 combination therapy regimens. Hemoglobin electrophoresis for HbAS and spectrophotometry to assess G-6-PD activity (deficient: <110 mU/109 erythrocytes) were performed at enrollment. HbSS children were excluded. To follow individual strains, parasitemic samples were genotyped by assessment of polymorphisms in merozoite surface protein 2 by nested PCR and capillary electrophoresis. Our primary
outcome was spontaneous clearance of parasites, a surrogate for effective antimalarial immunity. With HbAS and G-6-PD deficiency as our predictor variables, we used generalized estimating equations to estimate the relative risk of spontaneous clearance of parasites, adjusting for age. Ninety-nine children (16.5%) had HbAS and 62 (10.3%) were G-6-PD deficient. Genotyping revealed 2295 parasite strains in 370 subjects, giving an incidence of parasitemia of 2.8 per person year. Older children were more likely to clear infections once parasitemic (RR = 1.16 / year of age, 95%CI 1.10-1.23, p<0.001). Children with HbAS were significantly more likely to clear infections than those with HbAA (RR = 1.43, 95% CI 1.01-2.01, p=0.04). No association was found between G-6-PD deficiency and rate of clearance of infections. These results support the hypothesis that HbAS is protective against falciparum malaria, at least in part, due to increased immune clearance of parasites.

 

Frederick N. Baliraine, Samuel L. Nsobya, Jane Achan, JamesK. Tibenderana, Ambrose O. Talisuna, Bryan Greenhouse, PhilipJ. Rosenthal. LIMITED ABILITY OF PLASMODIUM FALCIPARUM PFCRT,PFMDR1, AND PFNHE-1 POLYMORPHISMS TO PREDICTQUININE IN VITRO SENSITIVITY OR CLINICAL EFFICACY INUGANDA.

 

Abstract presented at Atlanta ASTMH 2010

Quinine (QN) remains a standard drug for treating severe malaria in Africa, and it is increasingly used to treat uncomplicated malaria. However, failures of QN therapy are common. A recent effectiveness study in Uganda found that 23% of children treated with QN experienced recrudescence over 28 days of follow-up. Mechanisms of resistance to QN are uncertain, and it is unknown if QN treatment failures in Africa are due to drug resistance. Recent studies have identified associations between in vitro QN sensitivity and polymorphisms in the pfcrt, pfmdr1, and pfnhe1 genes, all of which encode putative transporters. In particular, for pfnhe1, which encodes a putative Na+/H+ exchanger, varied numbers of DNNND or DDNHNDNHNND repeats in ms4760 have been associated with different levels of in vitro QN sensitivity. To better characterize mediators of QN sensitivity and treatment failure, we characterized associations between genetic polymorphisms, in vitro QN sensitivity, and QN treatment responses in Uganda. Among 172 fresh clinical isolates tested (IC50 range 15.4 - 760.9 nM, based on HRP-2 ELISA assays), a trend of decreasing sensitivity to QN was observed with accumulation of pfmdr1 mutations at codons 86, 184 and 1246. All parasites had the pfcrt 76T mutation and wild type sequences at pfmdr1 1034 and 1042. Considering pfnhe1, sequence analysis showed that ms4760 is highly polymorphic, with 2 novel genotypes identified in addition to 19 previously reported. Two copies of either the DNNND or DDNHNDNHNND repeat, compared to 1 or >=3 repeats, were weakly associated with decreased QN sensitivity, but differences were not significant. Considering samples from 66 subjects treated in the clinical trial, none of the polymorphisms noted above predicted QN treatment failure. Our data suggest that known polymorphisms in pfcrt, pfmdr1, and pfnhe1, while associated with QN sensitivity in some studies, are not robust markers for QN resistance, and each likely will be of limited value as a tool for the surveillance of QN resistance in Africa.

 

Bryan Greenhouse, Lauren Gong, Bridget Nzarubara, Philip J.Rosenthal. DECLINING BLOOD-STAGE IMMUNITY IN THE SETTING OFDECREASING MALARIA INCIDENCE IN UGANDA.

 

Abstract presented at Atlanta ASTMH 2010

In endemic areas, protective immunity against Plasmodium falciparum usually increases with age and cumulative exposure. However, successfulmalaria control efforts are leading to decreased intensity of parasite exposure in many areas. The consequences of decreased exposure on antimalarial immunity are unclear. We recently suggested that an increasing risk of treatment failure in response to amodiaquine + sulfadoxine-pyrimethamine in a closely managed cohort of children in Kampala, Uganda, was due to declining immunity and not increased drug resistance, prompting us to investigate other manifestations of blood stage immunity. 601 randomly selected children from Kampala, aged 1-10, were followed for a median of 1.4 years. Blood smears were read every 30 days and any time a child presented with fever. Children with malaria, defined as asexual parasites on blood smear and fever, were treated after randomization to one of 3 combination therapy regimens. To follow parasite strains within individuals over time, parasitemic samples were genotyped by assessment of polymorphisms in merozoite surface protein 2 by nested PCR and capillary electrophoresis. We estimated associations between calendar time and two measures of immunity, the ability to avoid clinical illness despite parasitemia and the ability to spontaneously clear a parasite strain without receiving therapy, in both cases adjusting for age and accounting for repeated measures within individuals. During the
study the incidence of malaria fell from 1.6 to 0.9 episodes per person year and 375 children (62%) had at least one positive blood smear. The probability of avoiding symptoms despite parasitemia (OR=0.38 per year, 95%CI=0.26-0.56, p<0.001) and the probability of spontaneously clearing an infection (OR=0.29 per year, 95%CI=0.13-0.64, p<0.01) decreased significantly over time. These data suggest that clinically relevant and readily measurable blood stage immunity declined over a short period of time in our cohort, possibly due to improved access to effective therapy and decreasing parasite transmission intensity.

 

Edwin O. Ochong, Philip J. Rosenthal. EFFECTS OF PLASMODIUM FALCIPARUM DIHYDROPTEROATESYNTHASE MUTATIONS ON PARASITE FITNESS.

 

Abstract presented at Atlanta ASTMH 2010

The antifolates sulfadoxine-pyrimethamine (SP) and trimethoprimsulfamethoxazole (TMP/SMX) have potent activity against wild type Plasmodium falciparum, but activity is decreased due to resistance mediating mutations in many areas. However, SP remains the drug of choice for intermittent preventive therapy in pregnant women and children, and TMP/SMX is widely used to prevent opportunistic infections in those with HIV infection. Resistance to antifolates is mediated by a series of mutations in the target enzymes dihydrofolate reductase (DHFR) and dihydropteroate synthase (DHPS), key enzymes in the folic acid biosynthetic pathway. In East Africa, parasites commonly harbor 3 DHFR mutations (S108N, N51I and C59R) and 2 DHPS mutations (A437G and K540E) that mediate an intermediate level of resistance. Additional point mutations, seen more commonly outside Africa, mediate higher-level resistance. We are studying the impact of various resistance mediating mutations in DHFR and DHPS on the relative fitness of P. falciparum. To this aim, we are exploring the growth of parasites under different conditions and in competition assays. We are studying D10-strain parasites engineered to express DHPS with 1-3 mutations. In initial competition experiments, D10 wild-type and single mutant (A437G) strains outcompeted parasites with 2 (A437G + A581G or S436A + A437G) or 3 (S436A + A437G + K540E) mutations over 2 months of culture, as assessed by strain-specific PCR. Experiments to more stringently
characterize relative growth of these strains utilizing folate-limiting culture conditions and quantitative PCR and to evaluate parasites with mutationsin DHFR are underway. Our preliminary results suggest that resistance mediating mutations in DHPS engender a loss of fitness compared to that of wild type strains of P. falciparum.

2009, WASHINGTON DC, USA

Heidi Hopkins, Wilson Kambale, Lisa Bebell, ChristianDokomajilar, Sarah G. Staedke, Moses R. Kamya, Philip J.Rosenthal, Grant Dorsey.Comparison of microscopy, HRP2- and pLDH-basedrapid diagnostic tests for malaria at sites ofvarying transmission intensity in Uganda.

 

Abstract presented at Washington DC ASTMH 2009.

In Africa, malaria is generally diagnosed on clinical grounds alone, though presumptive treatment results in significant overuse of antimalarials. Microscopy, the standard for malaria diagnosis, remains unavailable to the majority of African patients. Malaria rapid diagnostic tests (RDTs) may offer a practical and reliable alternative for case management, but optimal strategies for different epidemiological settings have not been defined. We compared the diagnostic accuracy of expert microscopy and two RDTs in 1000 patients of all ages at each of seven sites of varying transmission intensity across Uganda, using as the gold standard expert microscopy
corrected for presence or absence of Plasmodium falciparum by PCR based on ribosomal RNA. Overall, HRP2 showed superior sensitivity across sites and age groups, while pLDH and expert microscopy showed higher specificity. At the site with lowest transmission, the negative predictive value (NPV) was excellent for all three tests, but the positive predictive value (PPV) was significantly better with microscopy and pLDH. At the remaining six sites with medium and high transmission, PPV was excellent for all three tests (≥87.3%), though slightly higher for microscopy and pLDH than for HRP2. HRP2 showed excellent NPV in patients of all ages at all sites (≥96.5%). In contrast, as transmission intensity increased, the NPV for both microscopy and pLDH declined significantly, especially for youngerpatients. For pLDH, in children under 5 years, NPV ranged from a peak of 98.9% at a low-transmission site, to just 49.0% at a high-transmission site; in patients aged 5 years and older, the NPV fell from 98.1% to 69.3%. The NPV of expert microscopy was very similar to that of pLDH across all sites and age ranges. In conclusion, considering diagnosis based on PCR as a gold standard, microscopy or pLDH are likely to provide the best diagnostic utility at sites with low transmission, while HRP2 is recommended for medium- and high-transmission areas.

 

Anne F. Gasasira, Moses Kamya, Neil Vora, Jane Achan,Fredrick Katera, Edwin Charlebois, Theodore Ruel, Diane Havlir,Philip Rosenthal, Grant Dorsey. Prophylactic Effect of Trimethoprim-sulfamethoxazole on Malaria in HIV-infectedChildren Living in Kampala, Uganda.

 

Abstract presented at Washington DC ASTMH 2009.

Daily trimethoprim-sulfamethoxazole (TS) reduces malaria risk substantially, but this effect may be compromised as antifolate resistance increases or when adherence is sub-optimal. We assessed the incidence of malaria and the prevalence of resistance-conferring mutations in members of two cohorts: 517 HIV-uninfected and 292 HIV-infected children aged 1-10 years. Daily TS and antiretroviral therapy (ART; based on WHO criteria) was prescribed for HIV-infected participants. HIV-uninfected participants did not receive TS. All participants were provided insecticide-treated bednets. Standardized protocols were used for malaria ascertainment and identification of resistance-mediating polymorphisms. The protective efficacy of TS was compared for three consecutive 9.5-month periods in 2006-08 using negative binomial regression models. Among HIV-infected subjects, 3-day TS adherence data were collected monthly and classified as optimal (no missed doses), inadequate (1-2 missed doses) or very poor (>2 missed doses). Generalized estimating equations were used to assess the relationship between adherence and malaria risk adjusting for repeated measures, CD4 level, age and ART use. TS use had a protective efficacy of 80% (0.10 vs. 0.45 episodes PPY, p<0.001) despite high prevalence of 5 resistance-mediating mutations (dhfr 51I, 108N, C59R; dhps 437G, 540E) in parasites infecting HIV-infected (92%) and uninfected (86%, p=0.22) subjects. The dhfr 164L mutation, which mediates high-level resistance, but is rare in Africa, was seen in 8% of HIV-infected, but only 1% of HIV-uninfected participants (p=0.001). TS efficacy and prevalence of mutations did not change over time. The odds of malaria were higher among HIV-infected subjects with very poor (OR 3.48, p<0.001) or inadequate (OR 2.96, p=0.024) compared optimal adherence. In summary, TS demonstrated good prophylactic efficacy against malaria despite high prevalence of markers of antifolate resistance, efficacy was diminished by poor drug adherence, and TS use was associated with increased prevalence of dhfr 164L.

 

Patrick Michael Newman, Humphrey Wanzira, Jane Achan,Moses Kamya, Diane Havlir, Philip J. Rosenthal, SarahWaldman, Grant Dorsey, Deborah Cohan, Tamara D. Clark. Placental Malaria as a Predictor of Low BirthWeight among HIV-Infected and Uninfected Womenin Tororo, Uganda.

 

Abstract presented at Washington DC ASTMH 2009.

For prevention of placental malaria (PM) in Uganda, pregnant women receive intermittent preventive therapy with sulfadoxine-pyrimethamine (IPT-SP), but HIV-infected women receive daily trimethoprim-sulfamethoxazole (TS). The risk of placental malaria is increased in the setting of HIV, but data on the prevalence of PM and the association of PM with adverse pregnancy outcomes such as low birth weight (LBW) in HIV-infected women on TS are lacking. We performed a cross-sectional study of HIV-infected and uninfected women (1:3 ratio) delivering at Tororo District Hospital, a region of very high malaria endemicity. PM was diagnosed by Giemsa-stained thick smear and Plasmodium falciparum PCR of placental blood. We assessed associations with LBW (<2500 grams) and HIV status. Results: We enrolled 517 women. 94% of women were on recommended chemoprophylaxis (TS for HIV-infected and IPT-SP for HIV-uninfected) and only these women were included in further analyses. Overall prevalence of PM was 8% when defined by positive blood smear and 25% when defined by positive PCR. PM by positive blood smear was associated with LBW among HIV-infected (RR 5.12, 95% CI 2.36-11.16) and HIV-uninfected (RR 2.25, 95% CI 1.07-4.75) women. Placentas which were positive by PCR but negative by blood smear were not associated with LBW in either group. There was no increased risk of PM by positive blood smear (OR 0.89, 95% CI 0.29-2.02) among HIV-infected vs. HIV uninfected women after controlling for gravidity. Prevalence of PM by blood smear of placental blood was low in this area of high malaria transmission. Overall rates of recommended chemoprophylaxis use were high. PM prevalence was similar among HIV-infected and HIV-uninfected women who were taking recommended chemoprophylaxis. PM by blood smear was associated with LBW. PCR was a more sensitive test than placental blood smear for PM, but PCR positivity without a positive smear did not predict LBW, and the clinical significance of placental PCR positivity remains uncertain.

 

Taylor Sandison, Jaco Homsy, Emmanuel Arinaitwe, Neil Vora,Abel Kakuru, Humphrey Wanzira, Victor Bigira, Julius Kalamya,Moses Kamya, Grant Dorsey, Jordan Tappero. A Randomized Clinical Trial of the ProtectiveEfficacy of Trimethoprim-SulfamethoxazoleProphylaxis against Malaria in HIV-exposed Children.

 

Abstract presented at Washington DC ASTMH 2009.

Trimethoprim-sulfamethoxazole (TS) prophylaxis is used throughout Africa to prevent opportunistic infections in HIV-infected and HIV-exposed (HIV uninfected infants born to HIV-infected mothers) infants. Observational studies suggest TS prophylaxis also protects HIV-infected children against malaria. However, data are limited regarding the effect of TS prophylaxis on the risk of malaria in HIV-exposed children. In an area of high malaria transmission in Uganda, we are conducting the first randomized clinical trial of TS protective efficacy against malaria among HIV-exposed infants. 203 HIV-exposed breastfeeding infants were enrolled and prescribed daily TS prophylaxis, per WHO guidelines, until confirmation of PCR-negative HIV status 6 weeks after cessation of breastfeeding. At this point, 185 children were randomized (median age at randomization= 9.6 months) to discontinue or continue TS prophylaxis through age 2 years. 18 HIV exposed children were not randomized as 10 children were withdrawn prior to randomization and 8 children seroconverted during breastfeeding. Malaria was diagnosed when a child presented with fever and a positive thick blood smear. The association between TS use and malaria incidence was estimated as an incidence rate ratio (IRR) using negative binomial regression. Among 98 infants randomized to continue TS, there were 239 malaria cases after 84.4 person-years (PY) (2.83 cases/PY). Among 87 infants randomized to stop TS, there were 338 malaria cases after 74.5 person-years (4.53 cases/PY). TS prophylaxis yielded a 39% reduction (IRR=0.61, 95%CI= 0.47-0.77, p<0.001) in malaria incidence. We are now following children beyond 2 years of age to compare age-specific malaria incidence between children who stopped TS after breastfeeding (35 cases/6.66 PY= 5.26 cases/PY) and children who stopped TS at age 2 years (18 cases/3.2 PY= 5.63 cases/PY) to evaluate for a post-TS rebound effect on malaria incidence. In our study, TS prophylaxis was modestly protective
against malaria in HIV-exposed infants when continued beyond the period of HIV exposure. This degree of protection is substantially lower than previously published in observational studies, possibly due to differences in antifolate resistance, transmission intensity, HIV infection, or other unmeasured confounders.

 

Vinay Gupta, Grant Dorsey, Philip Rosenthal, Bryan Greenhouse.Comparison of Genotyping Using Capillary vs.Gel Electrophoresis for Two Antimalarial Drug Efficacy Trials in Uganda.

 

Abstract presented at Washington DC ASTMH 2009.

In antimalarial drug efficacy trials in malaria endemic areas, molecular genotyping techniques are required to distinguish failures due to recrudescence from new infection after therapy. In 2007, the WHO recommended using capillary electrophoresis rather than gel electrophoresis for genotyping where feasible. This recommendation is based on increased discrimination of alleles with capillary electrophoresis, potentially reducing the risk of alleles matching by chance and being misclassified as a recrudescence. However, no direct evidence currently supports this recommendation. We compared efficacy results obtained with the two genotyping methods, using data and samples from two trials comparing artemether-lumefantrine (AL) and ihyroartemisininpiperaperaquine (DP); one in Kunungu, Uganda, where transmission intensity is moderate (EIR=7), and the other in Apac, Uganda, wheretransmission intensity is very high (EIR>1500). In both trials, samples from subjects with recurrent parasitemia were genotyped at the MSP2, GLURP, and MSP1 loci in a stepwise fashion to distinguish new infection from recrudescence. Laboratory personnel were blinded to the identity of samples. At present, we have completed analysis for MSP2 and GLURP. In Kunungu (n=408), of 20 pairs classified as recrudescences by gel, 11 (55%) were new infections by capillary; of 12 pairs classified as recrudescences by capillary, 3 (25%) were new infections by gel. The 42-day genotyping-adjusted failure rate was higher when using gel vs. capillary genotyping for both AL (7.5% vs. 5%) and DP (4% vs. 2.4%). In Apac (n=417), of 61 pairs classified as recrudescences by gel, 42 (69%) were new infections by capillary; of 28 pairs classified as recrudescences by capillary, 9 (32%) were new infections by gel. The 42-day failure rate was again higher when using gel vs. capillary genotyping for both AL (19% vs. 10%) and DP (15% vs. 6%). Our preliminary results, based on only the MSP2 and GLURP loci, show that using capillary vs. gel genotyping resulted in fewer classifications of clinical failures as recrudescences, especially in our high transmission site, likely due to improved allele discrimination of capillary electrophoresis.

 

Bryan Greenhouse, Benjamin Ho, Moses R. Kamya, TamaraD. Clark, Denise Njama-Meya, Bridget Nzarubara, CatherineMaiteki-Sebuguzi, Sarah G. Staedke, Philip J. Rosenthal, Grant
Dorsey, Chandy C. John Antimalarial antibodies are good markers of priorexposure but not protection against subsequentmalaria in children in Kampala, Uganda.

 

Abstract presented at Washington DC ASTMH 2009.

Individuals in malaria-endemic regions develop antibodies against multiple parasite antigens, but associations between antibody levels and protection against subsequent malaria remain uncertain. We enrolled a cohort of 438 children aged 1-10 from a region of Kampala where malaria incidence was previously found to be heterogeneous, with those living near a swamp having 4 times the incidence of those living 200 meters away. Children were treated for all episodes of malaria and monitored every 30 days for asymptomatic parasitemia. Plasma samples were collected at least 180 days after enrollment. For children with at least 1 year of follow-up after sample collection, IgG responses were assayed via ELISA to P. falciparum circumsporozoite protein (CSP), liver-stage antigen 1 (LSA1), merozoite surface protein 3 (MSP3), 3 variants of merozoite surface protein 1 (MSP1), and 2 variants of apical membrane antigen 1 (AMA1). Reponses to different antigens were analyzed for associations with antecedent environmental and host factors, and for associations with subsequent malaria incidence. Overall antibody prevalence ranged from 12% (CSP) to 29% (AMA1). Increasing age, residence within 25 meters of the swamp and a shorter interval between last documented parasitemia and the time of plasma collection were all significantly associated with higher levels of antibodies to all 5 antigens in multivariate analysis. Higher antibody levels significantly predicted higher incidence of subsequent malaria after adjustment only for age (incidence 6%-16% higher per doubling of antibody level), but not after adjustment for age, prior malaria incidence, and distance from the swamp. In summary, IgG levels to 3 bloodstage and 2 pre-erythrocytic antigens were all markers of prior parasite exposure, but they did not predict protection against subsequent malaria. The relationship between antimalarial antibodies and subsequent malaria incidence may be confounded by heterogenous exposure to parasites.

2008, NEW ORLEANS, LA, USA

Norah Mwebaza, Moses R. Kamya, Tamara D. Clark, GrantDorsey, Philip J. Rosenthal, Christopher J. Whitty, Sarah G.Staedke. Evaluation of home-based management of feverwith artemether-lumefantrine in urban Ugandanchildren: a randomized trial.

Abstract presented at New Orleans, LA, ASTMH 2008.

Home-based management of fever (HBMF), promoting presumptive treatment of febrile children with pre-packaged antimalarials, has been advocated to ensure prompt effective treatment of malaria. However, there are potential downsides to HBMF, and no data on the health impact
of HBMF using artemisinin-based combination therapies are available. We evaluated the impact of home delivery of artemether-lumefantrine (AL) for management of febrile illnesses in children on the incidence of antimalarial treatment and other clinical measures, as compared to the current standard of care in Kampala, Uganda. HBMF households were trained and given AL to keep at home for presumptive treatment of feverin participating children . Of 437 children randomized, 225 to HBMF and 212 to standard care, 365 (84%) completed 12 months of study followup. Significantly more febrile episodes were treated promptly with an effective antimalarial in the HBMF arm than in the standard care arm (58% vs. 8%, respectively, RR 7∙18, 95% CI 4∙58 - 11∙27, p<0∙0001). Comparing clinical outcomes at completion of the study, the proportion of participants in the HBMF arm with a positive thick blood smear was lower than in the standard care arm (2% vs. 10%, RR 0∙21, 95% CI 0∙07 - 0∙64, p=0∙006), but no other clinical differences were seen. Compared to the standard care group, the incidence of hospitalizations was lower in the HBMF arm (0∙23 vs. 0∙13, IRR 0∙55, 95% CI: 0∙31 - 0∙99, p=0∙047). The HBMF group received nearly twice the number of antimalarial treatments as the standard care group (4∙66 vs. 2∙53, IRR 1∙72, 95% CI: 1∙43 - 2∙06, p<0∙0001), and approximately five times the number administered for microscopically-confirmed cases of malaria in a comparable cohort of
children (4∙66 vs. 1∙03, IRR 5∙12, 95% CI: 4∙24 - 6∙35, p<0∙0001). In this urban setting, HBMF with home delivery of AL substantially improved prompt treatment of fever with effective antimalarials, but had little impact on clinical outcomes. The lower incidence of hospitalization
observed in the HBMF arm suggests a clinical benefit, but at the cost of substantial over-treatment with antimalarials.

 

Heidi Hopkins, Alex Ojaku, Adoke Yeka, Patrick Angutoko,John Ategeka, Robert Okiror, Peter Olwoch, Umaru Ssekabira,Carol Asiimwe, Jane Nabakooza, John B. Rwakimari, LydiaMpanga Sebuyira, Fred Wabwire Mangen, Grant Dorsey. Effectiveness and safety of training in fever case management and RDT use at health centers inUganda.

 

Abstract presented at New Orleans, LA, ASTMH 2008.

In Africa, malaria is typically diagnosed clinically, though presumptive treatment results in significant overuse of antimalarials. Malaria rapid diagnostic tests (RDTs) may offer a reliable alternative, but effective training for health workers is a key challenge in RDT implementation. We designed a training program in fever case management incorporating RDTs, targeted to staff with limited formal education who work at peripheral health centers in Uganda. We then evaluated its clinical effectiveness and safety as compared with standard-of-care presumptive treatment, for the management of patients who present with suspected malaria at government health centers without microscopy in 3 different endemic zones of Uganda. In each zone, one health center was randomly selected to receive training, while a comparable health center serves as a control. Data collection is on-going; preliminary results from a sample of patients in one zone are presented here. At the health center that received training and RDTs, after the intervention, 93 of 165 patients (56%) were tested with RDTs, and of these, 57 (61%) were positive. At this health center, 127 of 165 (77%) patients were prescribed an antimalarial before RDTs were introduced and 37 of 165 (22%) patients were prescribed an antimalarial after RDTs were introduced. In contrast, at the health center that did not receive RDTs or training, 132 of 210 (63%) patients were prescribed an antimalarial before the intervention and 163 of 250 (65%) patients were prescribed an antimalarial after the intervention. The relative risk (RR) for prescribing an antimalarial after vs before the intervention was 0.29 (95% CI 0.22-0.39) at the health center where RDTs were introduced and 1.04 (95% CI 0.90-1.19) at the health center where RDTs were not introduced (p<0.0001 for test of homogeneity of RRs). The proportion of patients with a satisfactory outcome 5 days after presentation was similar at the centers with and without RDTs (91% vs. 90%, p=1.0). A basic training program in fever case management incorporating RDTs substantially reduced the proportion of patients prescribed an Antimalarial without adversely affecting outcomes.

 

Samuel L. Nsobya, Moses Kiggundu, Moses Joloba, GrantDorsey, Philip J. Rosenthal. Complexity of Plasmodium falciparum clinicalsamples from Uganda during short-term culture.

 

Abstract presented at New Orleans, LA, ASTMH 2008.

Plasmodium falciparum infections are commonly polyclonal. Not all isolated parasites successfully grow in culture, and it is unclear how well in vitro culture represents the complexity of clinical infections. We characterized changes in complexity of infection (COI) during short-term culture of parasites from children in Kampala, Uganda with uncomplicated malaria. Of 211 available samples, 98 were successfully cultured for at least 9 days. Parasite density at diagnosis was greater in samples that successfully grew for 9 days (mean 30,400/μl) than in those that did not (11,500/μl). COI was assessed daily for 9 days based on analysis of polymorphic regions of the msp-2 gene in parasite DNA extracted from dried blood spots. For 53 samples, only a single genotype was detected atculture initiation (Day 0). The mean COI at was 1.73 at Day 0,  remained stable for the first 4 days of culture, and then decreased gradually to 1.56 on Day 8. To gain insight into the sensitivity of single time point assessment of COI, we followed the appearance of new strains after Day 0. Strains not present on Day 0 were first identified on Days 1-5 in 20 cultures; half of these appeared on Day 1. Thus, the Day 0 genotype understated the true COI in 20% of samples. We were also interested in the loss of strains after Day 0. Strains disappeared after Day 0 in 25 (56%) of 45 cultures that were initially mixed. Upon analysis by PCR and restriction endonuclease digestion, persisting strains more commonly had drug-sensitive wild type dhfr (C59) and dhps (K540), and mutant pfmdr-1 (86Y) sequences. Thus, initial genotypes offer an imperfect representation of clinical COI, and loss of strains in culture may be due to diminished fitness of some drug resistant strains. Our study highlights potential elimitations both in the use of single time point assessment of COI as a baseline for drug efficacy determination and the reliability of associations between clinical outcomes and genotypes of stably cultured parasites.

 

Fatima Nawaz, Samuel L. Nsobya, Moses Kiggundu, MosesJoloba, Bryan Greenhouse, Grant Dorsey, Philip Rosenthal.Selection of Plasmodium falciparum withdiminished response to amodiaquine followingtreatment with combination therapy in Uganda.

 

Abstract presented at New Orleans, LA, ASTMH 2008.

Despite some known resistance, amodiaquine (AQ) remains a key component of antimalarial therapy, particularly when paired with artesunate (AS) or sulfadoxine-pyrimethamine (SP). It is unclear how readily resistance will develop to AQ when it is used in combination chemotherapy. We studied the impact of AQ-containing therapies on the sensitivity of parasites causing recurrent infections soon after prior therapy. We collected data for 61 Plasmodium falciparum samples from patients who were treated during 2006-2007 with AQ/SP, AQ/AS, or artemetherlumefantrine (AL) for uncomplicated malaria. These samples were placed in culture using standard methods, and in vitro sensitivity to the principal AQ metabolite desethylamodiaquine was measured by comparing growth to that of untreated controls with a histidine rich protein-2-based ELISA. Resistance-mediating polymorphisms were also evaluated from parasite DNA extracted from dried blood spots. Parasites from subjects who were previously treated with AQ/SP or AQ/AS within 12 weeks were less sensitive to AQ (n=16; mean IC50 63.7 nM; range 12.7-158.3 nM) than were parasites from those not treated with an AQ-containing regimen within 12 weeks (n=45; mean IC50 38.3 nM; p=0.095 (Kruskal-Wallis rank test); range 6.3-184.7 nM) or only those in a treatment arm that did not contain AQ (AL subjects; n=22; mean IC50 31.3 nM; p=0.017; range 6.3-121.8 nM). The proportion of strains with polymorphisms expected to mediate diminished response to AQ (pfmdr-1 N86Y and D1246Y) increased after prior AQ therapy, although differences between treatment groups were not significant. Our findings show that therapy with AQ rapidly selects for diminished response to this drug, suggesting that AQ-containing combination regimens may rapidly lose efficacy in Africa. However, the mechanism of diminished AQ response is probably not fully explained by known mutations in pfmdr-1, and additional studies to identify mechanisms of resistance to AQ are needed.

 

Emmanuel Arinaitwe, Taylor Sandison, Jaco Homsy, JuliusKalamya, Abel Kakuru, Humphrey Wanzira, Neil Vora, Philip J.Rosenthal, Moses Kamya, Jordan W. Tappero, Grant Dorsey. Artemether-lumefantrine versusdihydroartemisinin-piperaquine for the treatmentof uncomplicated malaria: a randomizedlongitudinal trial in a cohort of Ugandan infants.

 

Abstract presented at New Orleans, LA, ASTMH 2008.

Artemisinin-based combination therapy (ACT) is widely advocated for the treatment of uncomplicated malaria, however limited data exists on efficacy in young children. This study compared two leading ACTs in a cohort of young children living in a high transmission area of Uganda. From August 2007 to January 2008 we recruited a cohort of 301 HIV uninfected children aged 6weeks-9months. All children were provided with standard medical care, insecticide treated nets, and trimethoprimsulfamethoxazole prophylaxis during breastfeeding if born to HIV-infected mothers. When children were diagnosed with their first episode of uncomplicated malaria, they were randomized to artemether-lumefantrine (AL) or dihydroartemisinin-piperaquine (DP). The same therapy was given for all subsequent episodes of uncomplicated malaria. Through March 2008, a total of 59 children were randomized to AL (121 treatments), and 71 children to DP (136 treatments). After 28 days of follow-up, AL was associated with a significantly higher risk of recurrent parasitemia unadjusted by genotyping) compared to DP (35.0% vs. 11.2%, p<0.0001). Appearance of gametocytes after therapy was similar for AL and DP (0% vs. 3.2%, p=0.45). Mean hemoglobin recovery was similar for AL and DP (0.67 vs. 0.89 gm/dL, p=0.27). Both regimens were safe and well tolerated with the exception of one patient who developed severe anemia following repeated treatments with DP. Our preliminary results indicate that, in a high transmission region, the antimalarial efficacy of DP was superior to that of AL; Genotyping to distinguish recrudescence from new infections, is on going.

 

Julia Mwesigwa, Bryan McGee, Joan Nakayaga, TamaraClark, Grant Dorsey, Philip J. Rosenthal, Niklas Lindegardh,Moses R. Kamya, Francesca Aweeka, Sunil Parikh. Pharmacokinetics of Artemisinin CombinationTherapy in Children in Kampala, Uganda.

 

Abstract presented at New Orleans, LA, ASTMH 2008.

The World Health Organization (WHO) recommends the use of artemisinin-based combination therapies (ACT) for the treatment of uncomplicated malaria. In response to increasing antimalarial drug resistance, the Uganda Ministry of Health advocates the use of ACTs, including artemether-lumefantrine (AL) and artesunate/amodiaquine(AQ/AS) as first-line antimalarial drugs. Despite wide-spread use, pharmacokinetic (PK) data informing optimum dosing of these drugs is limited, especially in children. Compared to adults, children may exhibit altered activity of cytochrome P450 and UDP-glucuronosyltransferase metabolic pathways, thereby affecting their ACT PK exposure and potentially altering their risk of treatment failure. We evaluated PK parameters in Ugandan children aged 5-13 years with uncomplicated malaria treated with AL or AQ/AS. Twenty children each were evaluated for the AL and AQ/AS treatment arms. Blood samples were drawn just prior to treatment and at 0, 2, 4, 8, 24 and 120 hours followingthe last dose of the 3 day regimen of AL (twice daily) or AQ/AS (once daily). Sample collection has been completed, and plasma is currently being analyzed for concentrations of artemether, the active metabolite dihydroartemisinin (DHA), lumefantrine, and the metabolite desbutyllumefantrine for the AL regimen and artesunate, DHA, amodiaquine, and the active metabolite desethylamodiaquine for the AQ/AS regimen. These data will allow the calculation of PK parameters, including the area under the plasma concentration versus time curve (AUC), apparent clearance (CL/F) and half-life, which will be presented and compared to historical data from adult subjects. This will be, to our knowledge, the first intensive PK study carried out in children in subSaharan Africa. Results will allow optimization of antimalarial treatment guidelines for African children.

 

Hasifa F. Bukirwa, Vincent Yau, Ruth Kigozi1, Linda Quick,Myers Lugemwa, Gunawardena Dissanayake, Sarah G. Staedke,Moses R. Kamya, Fred Wabwire-Mangen, Grant Dorsey. Assessing the impact of indoor residual sprayingon malaria indicators using a sentinel sitesurveillance system in Western Uganda.

 

Abstract presented at New Orleans, LA, ASTMH 2008.

Accurate assessment of the impact of malaria interventions is necessary to optimize control efforts. Indoor Residual Spraying (IRS) has been increasingly advocated as an effect method of malaria control in Africa, especially in areas of low-to-moderate transmission. However, there are limited contemporary data on the impact of IRS on key malaria indicators. We evaluated the impact of an IRS campaign in Kanungu District of Western Uganda, an epidemic prone area with an EIR measured to be 6 infective bites per person year in 2001. Approximately 45,000 households covering a population of 190,000 persons were sprayed with the shortacting, synthetic pyrethroid lambda-cyhalothrin between February and March 2007. We used an existing sentinel site surveillance system to measure the impact of the IRS campaign on key malaria indicators measured on all patients presenting to the outpatient department of a government health center. Pre and post IRS data were compared using time-series analysis controlling for temporal trends and rainfall. A total of 14,942 patients (23% under 5 years) were evaluated in the 36 weeks prior to IRS and 18,482 patients (33% under 5 years) were evaluated in the 48 weeks after IRS. The proportion of patients under 5 years referred for microscopy with a positive blood smear decreased from 33.2% prior to IRS to 6.2%, 4.1%, and 10.1% in the periods 1-16 weeks, 17-32 weeks, and 33-48 weeks after IRS, respectively (p<0.0001 for all pairwise comparisons). The proportion of patients 5 years or older referred for microscopy with a positive blood smear decreased from 27.4% prior to IRS to 12.3%, 15.5%, and 21.8% in the periods 1-16 weeks, 17-32 weeks, and 33-48 weeks after IRS, respectively (p<0.05 for all pairwise comparisons). IRS was associated with a significant decline in the proportion of patients suspected of malaria with a positive blood smear, especially in children under 5 years. However, there was some evidence that the benefit of IRS began to wane after 32 weeks. Sentinel surveillance systems are a useful method for evaluating malaria interventions and we
recommend  their use.

 

Bryan Greenhouse, Madeline Slater, Denise Njama-Meya,Bridget Nzarubara, Catherine Maiteki-Sebuguzi, Tamara D.Clark, Moses R. Kamya, Alan Hubbard, Philip J. Rosenthal,Grant Dorsey.Increasing Risk of Treatment Fa ilure withAntimalarial Combination Therapy: Para site andHost Factors.

 

Abstract presented at New Orleans, LA, ASTMH 2008.

Clinical response to antimalarial therapy is dependent on both drug parasite and host-parasite interactions. We prospectively measured response to treatment with amodiaquine + sulfadoxine-pyrimethamine (AQ/SP) within a cohort of children in Kampala, Uganda between 2004 and 2007. Response to therapy was measured as the risk of treatment failure (TF) by day 63 after therapy, adjusted by genotyping. Over a 29 month period, we observed a significant increase in the risk of TF, from 5% at the beginning of the study to 21% at the end (HR=2.4/ yr, p=0.002). The prevalence of predicted molecular markers of drug resistance (DHFR 51I, 59R, 108N, 164L; DHPS 437G, 540E; PfCRT 76T; PfMDR1 86Y, 184F, 1034C, 1042D, 1246Y) did not increase over this time, and adjusting for these markers did not change the association between time and TF. Thus, decreasing efficacy of AQ/SP was not explained by known parasite factors. To establish whether differences in host immunity might contribute to the increasing risk of TF, we considered exposureas a surrogate of immunity. Those living in the area of highest malaria incidence had a significantly lower risk of TF (5%) compared to those living in the area of lowest malaria incidence (18%) (HR=0.26, p=0.003). To test the hypothesis that declining immunity within subjects was responsible for the increase in TF over time, we used the presence of recent asymptomatic parasitemia (AP) as a time-dependent surrogate of immunity. We compared the association between time and the risk of TF in a model which included recent AP, markers of drug resistance, geography, and age, with a model which did not include recent AP. Including recent AP in the model reduced the association between time and risk of treatment failure (HR=2.8/yr, p=0.002 vs. HR=1.4/yr, p=0.38), suggesting that declining immunity in our subjects explained in large part the increase in TF over time. Our results suggest that effective malaria control interventions may lead to declining host immunity and subsequently an increased risk of TF, especially with suboptimal antimalarial therapy.

 

Sunil Parikh, Marla K. Johnson, Moses R. Kamya, GrantDorsey, Philip J. Rosenthal. Glucose 6-Phosphate Dehydrogenase (G6PD) Deficiency Genotype-Phenotype Correlations inMalaria Association Studies.

 

Abstract presented at New Orleans, LA, ASTMH 2008.

We explored the relationship between G6PD genotype (G202A) and phenotype (enzyme assay) and the incidence of malaria in a cohort of 596 children, aged 1-10, recruited from a census population in Kampala and followed for 2 years. G6PD genotype was assessed based on the predominant East African allele (G6PD A-, G202A) and phenotype by quantitative spectrophotometric methods. The prevalence of G6PD deficiency was significantly higher by mutational analysis (99/591; 16.8%), than by enzymatic assay (62/599; 10.4%). In females, the prevalence of G6PD deficiency was three-fold higher when assessed by mutational analysis compared to enzymatic assay (64/284; 22.5% vs (20/285; 7.0%, respectively (p<0.01). Heterozygous females accounted for the majority (46/54) of children who had a mutant genotype yet normal enzyme; males accounted for the majority (12/16) of children who were wildtype at G202A, yet deficient by enzyme assay. To explore the impact of these discrepant measures upon the association of G6PD status and malaria incidence, we compared the two measures in a longitudinal cohort of children. A total of 695 episodes of uncomplicated malaria were diagnosed after 901 person years of follow-up. Multivariate analysis using generalized estimating equations was used to identify independent predictors of malaria incidence. Using the enzymatic assay, G6PD deficiency was associated with significant protection from uncomplicated malaria only in females (RR=0.48, 95%CI 0.31-0.75). This protection was comparable to the protection afforded by the usage of insecticide-treated bednets (RR=0.52, 95%CI 0.32-0.83). However, when G6PD status was assessed by genotyping the G202A allele, this association no longer was present (RR=0.96; 95%CI 0.69-1.33). Thus, there was substantial discordance between enzymatic and genotypic assays for G6PD deficiency. This observation may explain, in part, the heterogeneity of published association studies to date. Potential explanations and implications for these findings will be discussed.

 

Taylor Sandison, Jaco Homsy, Emmanuel Arinaitwe, NeilVora, Abel Kakuru, Humphrey Wanzira, Julius Kalamya, MosesKamya, Grant Dorsey, Jordan W. Tappero. A Randomized Clinical Trial of the ProtectiveEfficacy of Trimethoprim-SulfamethoxazoleProphylaxis against Malaria in HIV-exposedChildren.

 

Abstract presented at New Orleans, LA, ASTMH 2008.

Malaria is a leading cause of death in Africa for children under 5 years of age. Trimethoprim-sulfamethoxazole (TS) prophylaxis is used throughout Africa to prevent opportunistic infections in HIV-infected and HIV-exposed (HIV-uninfected children born to HIV-infected mothers) children. Recent studies show that TS prophylaxis also protects HIV-infected children against malaria. However, there are no studies regarding the protective efficacy of TS prophylaxis in HIV-exposed children. We are conducting a randomized clinical trial in an area of perennial high malaria transmission in Uganda. We enrolled 201 HIV-exposed infants aged 6 weeks-9 months. All children were breastfeeding and taking TS prophylaxis at enrollment. We provided insecticide-treated nets at enrollment and follow the children for all their healthcare needs until the age of 21 months. Per World Health Organization and Uganda Ministry of Health recommendations, each HIV-exposed child was continued on TS prophylaxis until DNA PCR confirmation of negative HIV status 6-8 weeks after cessation of breastfeeding. Each child was then randomized to continue or discontinue TS prophylaxis. Malaria was diagnosed when a child presented with a new episode of fever and a positive thick blood smear. Generalized estimating
equations were used to measure the association between TS and the risk of malaria adjusting for repeated measures. Among 201 HIV-exposed infants enrolled, 110 have stopped breastfeeding, been confirmed HIV-uninfected, and been randomized to continue or discontinue TS prophylaxis. The median age at randomization is 9 months (range: 6.2-16.5). There have been 32 malaria cases among 57 HIV-exposed children randomized to continue TS after 12.0 person-years of follow-up time (2.66 cases/person-year). There have been 51 malaria cases among 53 HIV-exposed children randomized to discontinue TS after 11.5 person years of follow-up time (4.44 cases/person-year). After adjusting for age, TS prophylaxis was associated with a 38% reduction (95%CI= 2%-61%, p=0.04) in the risk of malaria. These findings suggest that TS prophylaxis is modestly protective against malaria in HIV-exposed children when continued beyond the period of exposure to HIV. Data will continue to accrue through the next six months and will update prior to the annual ASTMH meeting.

 

Neil Vora, Jaco Homsy, Emmanuel Arinaitwe, Taylor Sandison,Abel Kakuru, Humphrey Wanzira, Julius Kalamya, MosesKamya, Jordan W. Tappero, Grant Dorsey. The effect of breastfeeding on the risk of malariaamong children born to HIV-infected mothers.

 

Abstract presented at New Orleans, LA, ASTMH 2008.

Breastfeeding protects infants against some infectious diseases, but data are limited on whether it reduces the risk of malaria. We assessed whether breastfeeding is protective against malaria among a cohort of HIV-exposed children (HIV-uninfected children born to HIV-infected mothers) and HIV-infected children in an area of high malaria transmission in Uganda. HIV-exposed and HIV-infected children all taking trimethoprimsulfamethoxazole (TS) prophylaxis and given ITNs were enrolled between 1.5 and 9 months (mo) of age and followed to 15 mo of age. Malaria was diagnosed when a child presented with a fever and a positive blood smear. Date of breastfeeding cessation was determined using monthly questionnaires. Among 189 HIV-exposed children, 137 (72%) had stopped breastfeeding at a median age of 7.0 mo (IQR: 6.1-8.8). Among 45 HIV-infected children, 8 (18%) had stopped breastfeeding at a median age of 4.4 mo (IQR: 2.6-8.5). Generalized estimating equations were used to model the association between breastfeeding and the daily risk of malaria adjusting for repeated measures. Due to significant effect modification, data was stratified into two age groups (6-<9 mo and 9-<15 mo) while adjusting for age within each stratum. Among 6-9 mo old HIV-exposed children, the incidence of malaria was similar among those who were breastfeeding and those who were not (1.30 vs 1.37 episodes PPY; RR=1.17; p=0.63). HIV-exposed children 9-15 mo old who were breastfeeding had a lower risk of malaria compared to those not breastfeeding (0.77 vs 2.75 PPY; RR=0.32; p=0.004). Among 6-9 mo old HIV-infected children, the incidence of malaria was similar among those who were breastfeeding and those who were not (1.05 vs 1.49 PPY; RR=0.75; p=0.76). HIV-infected children 9-15 mo old who were breastfeeding had a lower risk of malaria compared to those not breastfeeding (1.09 vs 3.86 PPY; RR=0.31; p=0.03). These findings suggest that breastfeeding is associated with a reduced risk of malaria among HIV exposed and HIV-infected children taking TS prophylaxis between the ages of 9 and 15 mo.

 

Yeka Adoke, Grant Dorsey, Moses R. Kamya, AmbroseTalisuna, Myers Lugemwa, John B. Rwakimari, Sarah G.Staedke, Philip J. Rosenthal, Fred W. Mangen, Hasifa Bukirwa. Artemether-Lumefantrine VersusDihydroartemisinin-Piperaquine for Treatment ofUncomplicated Fa lciparum Malaria: A RandomizedTrial to Guide National Policy in Uganda.

 

Abstract presented at New Orleans, LA, ASTMH 2008.

Artemisinin-based combination therapies (ACTs) have been strongly advocated for use in Africa but obstacles to their widespread use remain. Uganda recently adopted artemether-lumefantrine (AL) as the recommended first-line treatment for uncomplicated malaria. However, AL has several limitations, including a twice-daily dosing regimen, recommendation for administration with fatty food, and a high risk of reinfection soon after therapy in high transmission areas. We compared the efficacy and safety of AL with DP in Kanungu, an area of moderate malaria transmission in Uganda. Patients aged 6 months to 10 years with uncomplicated falciparum malaria were randomized to therapy and followed for 42 days. Genotyping was used to distinguish recrudescence from new infection. Of 414 patients enrolled, 408 completed follow-up. Compared to patients treated with AL, patients treated with DP had a significantly lower risk of recurrent parasitaemia (33.2% vs. 12.2%; risk difference = 20.9%, 95% CI 13.0-28.8%) but no statistically significant difference in the risk of treatment failure due to recrudescence (5.8%
vs. 2.0%; risk difference = 3.8%, 95% CI -0.2-7.8%). The prevalence of fever was similar over the first 3 days of follow-up in the two treatment groups. Both treatments produced rapid clearance of parasitemia with no parasites detected by Day 3. Patients treated with DP also had a lower risk of developing gametocytaemia after therapy (4.2% vs. 10.6%, p=0.01). Both drugs were safe and well tolerated. DP is highly efficacious, and operationally preferable to AL   because of a less intensive dosing schedule and requirements.

2007, PHILIDELPHIA, PA, USA


Gasasira AF, Kamya MR, Achan J, Mebrahtu T, Kalyango JN, Ruel T, Charlebois E, Staedke SG, Kekitiinwa A, Rosenthal PJ, Havlir D, Dorsey G. High risk of neutropenia among HIV-infected children following treatment with artesunate plus amodiaquine for uncomplicated malaria in Uganda. Presented at the 56th Annual ASTMH meeting, November 04-08, 2007.


Achan, J, Ruel TD, Gasasira AF, Charlebois ED, Rosenthal PJ, Dorsey G, Kamya MR, Kekitiinwa A, Wong J, Havlir D, and the CHAMP team. Dramatic reductions in HIV RNA among HIV-infected children with acute measles in Uganda. Presented at the 56th Annual ASTMH meeting, November 04-08, 2007.


Yoel Lubell, Hopkins H, Whitty CJM, Staedke SG, Mills A. "Modelling the costs and benefits of HRP2 and pLDH RDTs for the detection of P. falciparum in Uganda," 56th annual meeting of The American Society of Tropical Medicine & Hygiene, Philadelphia, Pennsylvania, Nov 2007.


Hopkins H, Kambale W, Bebell L, Dokomajilar C, Kamya MR, Staedke SG, Rosenthal PJ, Dorsey G. "Comparison of microscopy, HRP2- and pLDH-based rapid diagnostic tests for malaria at sites of varying transmission intensity in Uganda," 56th annual meeting of The American Society of Tropical Medicine & Hygiene, Philadelphia, Pennsylvania, Nov 2007.


Bebell, LM, Gasasira AF, Kiggundu M, Dokomajilar C, Kamya MR, Charlebois ED, Havlir D, Rosenthal PJ, Dorsey G. "HIV-1 infection in patients referred for malaria blood smears at government health clinics in Uganda. ASTMH meeting," November 4-8, 2007.


Nankabirwa J, Kalyango J, Karamagi C, Kamya M, Dorsey G, Peterson S, Hopkins H. Case management and outcomes for children presenting with fever and negative blood smears at government health centers in Uganda, 56th annual meeting of The American Society of Tropical Medicine & Hygiene, Philadelphia, Pennsylvania, Nov 2007

2006, ATLANTA, GA, USA


Sarah Staedke, Mwebaza N, Kamya M, Dorsey G, Rosenthal PJ, Whitty CJM. "Evaluation of home-based management of fever in urban Ugandan children," 55th annual meeting of The American Society of Tropical Medicine & Hygiene, Atlanta, Georgia, Nov 2006


Hasifa Bukirwa, Lubanga R, Nayiga S, Hopkins H, Yeka A, Talisuna A, Staedke S. "Pharmacovigilance of antimalarial treatment in Uganda: Establishing a surveillance system," 55th annual meeting of The American Society of Tropical Medicine & Hygiene, Atlanta, Georgia, Nov 2006


Heidi Hopkins, Kambale W, Staedke S, Kamya M, Rosenthal PJ, Dorsey G. "Comparison of HRP2- and pLDH-based rapid diagnostic tests (RDTs) for malaria in Uganda," 55th annual meeting of The American Society of Tropical Medicine & Hygiene, Atlanta, Georgia, Nov 2006


Kamya MR, Gasasira AF, Achan J, Mebrahtu T, Kekitiinwa A, Charlebois ED, Rosenthal PJ, Havlir D, Dorsey G. "The effect of co-trimoxazole prophylaxis and insecticide-treated bednets on the risk of malaria among HIV infected Ugandan children. ASTMH 55th Annual Meeting, November 12-16, 2006, Scientific Session 37, HIV in the Tropics.


Tamara D. Clark, Njama DM, Staedke S, Nzarubara B, Maiteki CS, Kamya M, Rosenthal PJ, Dorsey G. Predictors of malaria incidence in a cohort of children living in Kampala, Uganda. The American Society of Tropical Medicine & Hygiene, Atlanta, Georgia, Nov 2006

2005, Washington DC, USA


Sulggi A Lee, Yeka A, Nsobya SL, Dokomajilar C, Rosenthal PJ, Talisuna A, Dorsey G. "Complexity of Plasmodium falciparum infections and antimalarial drug efficacy at seven sites in Uganda," American Society of Tropical Medicine & Hygiene 54th Annual Meeting, Washington, DC, Dec 2005.

2004, MIAMI BEACH, FL, USA


Grant Dorsey. "Dihydrofolate reductase and dihydropteroate synthase genotypes and clinical response to sulfadoxine-pyrimethamine therapy alone and in combination," American Society of Tropical Medicine & Hygiene 53rd Annual Meeting, Miami Beach, Florida, Nov 2004.


Sarah Staedke. "Combination antimalarial therapies: safety and assessment of adverse events in Uganda," American Society of Tropical Medicine & Hygiene 53rd Annual Meeting, Miami Beach, Florida, Nov 2004.


Adoke Yeka. "Artemisinin verses non-artemisinin combination therapy for uncomplicated malaria: randomised clinical trials from four sites in Uganda," American Society of Tropical Medicine & Hygiene 53rd Annual Meeting, Miami Beach, Florida, Nov 2004.


Heidi Hopkins, Njama-Meya D, Kamya MR, Dorsey G, Rosenthal PJ, Staedke SG. "Socioeconomic factors and malaria prevention and treatment practices in urban Uganda," abstract 755, American Society of Tropical Medicine & Hygiene 53rd Annual Meeting, Miami Beach, Florida, Nov 2004


Heidi Hopkins, Dorsey G, Barugahare B, Okello M, Kityo C, Mugyenyi P, Kamya MR, Rosenthal PJ, Cao H, Eggena M. "Evaluation of T cell activation as a predictor for treatment failure in uncomplicated malaria," abstract 768, American Society of Tropical Medicine & Hygiene 53rd Annual Meeting, Miami Beach, Florida, Nov 2004

2003, PHILIDEPHIA, PA, USA


Grant Dorsey. "Combining artesunate to sulfadoxine-pyrimethamine prevents increased rates of clinical treatment failure for sequential episodes of uncomplicated malaria in Uganda," American Society of Tropical Medicine & Hygiene 52nd Annual Meeting, Philadelphia, Pennsylvania, Dec 2003.


Anne Gasasira. "The impact of age, temperature and parasite density on treatment outcomes from antimalarial clinical trials in Kampala, Uganda," American Society of Tropical Medicine & Hygiene 52nd Annual Meeting, Philadelphia, Pennsylvania, Dec 2003.


Sam Nsobya. "Molecular evaluation of the natural history of asymptomatic parasitemia in Ugandan Children," American Society of Tropical Medicine & Hygiene 52nd Annual Meeting, Philadelphia, Pennsylvania, Dec 2003.


Sarah Staedke. "Proximity to mosquito breeding sites as a risk factor for clinical malaria in an urban cohort of Ugandan children," American Society of Tropical Medicine & Hygiene 52nd Annual Meeting, Philadelphia, Pennsylvania, Dec 2003.

2001, ATLANTA, GA USA


Anne Gasasira. "Chloroquine or amodiaquine combined with Fansidar for the treatment of uncomplicated malaria in Kampala, Uganda," American Society of Tropical Medicine & Hygiene 50th Annual Meeting, Atlanta, Georgia, Nov 2001.


Grant Dorsey. "Longitudinal assessment of combination therapies for falciparum malaria in Kampala, Uganda: Improved efficacy and reduction of disease incidence," American Society of Tropical Medicine & Hygiene 50th Annual Meeting, Nov 2001.


Sarah Staedke. "Mutations in P. falciparum dihydrofolate reductase and dihydropteroate synthase genes and resistance to sulfadoxine/pyrimethamine in Kampala, Uganda," American Society of Tropical Medicine and Hygiene Annual Meeting, Nov 2001

2000, HOUSTON, TX, USA


Sarah Staedke. "The comparative efficacy of sulfadoxine-pyrimethamine, amodiaquine, and combination therapy for treatment of uncomplicated malaria in Kampala, Uganda," American Society of Tropical Medicine & Hygiene 49th Annual Meeting, Nov 2000.


Grant Dorsey. "Previously identified polymorphisms in pfcrt and pfmdr-1 are not predictive of in vivo chloroquine response in Kampala, Uganda," American Society of Tropical Medicine & Hy"giene 49th Annual Meeting, Nov 2000.

1999, WASHINGTON DC, USA


Grant Dorsey. "Epidemiological risk factors for chloroquine resistant malaria in children and adults in Kampala, Uganda," American Society of Tropical Medicine & Hygiene 48th Annual Meeting, Nov 1999.