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Glucose-6-phosphate dehydrogenase (G6PD) deficiency is believed to confer protection against Plasmodium falciparum malaria, but the precise nature of the protective effect has proved difficult to define as G6PD deficiency has multiple allelic variants with different effects in males and females, and it has heterogeneous effects on the clinical outcome of P. falciparum infection. Here we report an analysis of multiple allelic forms of G6PD deficiency in a large multi-centre case-control study of severe malaria, using the WHO classification of G6PD mutations to estimate each individual’s level of enzyme activity from their genotype. Aggregated across all genotypes, we find that increasing levels of G6PD deficiency are associated with decreasing risk of cerebral malaria, but with increased risk of severe malarial anaemia. Models of balancing selection based on these findings indicate that an evolutionary trade-off between different clinical outcomes of P. falciparum infection could have been a major cause of the high levels of G6PD polymorphism seen in human populations.

BackgroundCurrent artesunate (ARS) regimens for severe malaria are complex. Once daily intramuscular (i.m.) injection for 3 d would be simpler and more appropriate for remote health facilities than the current WHO-recommended regimen of five intravenous (i.v.) or i.m. injections over 4 d. We compared both a three-dose i.m. and a three-dose i.v. parenteral ARS regimen with the standard five-dose regimen using a non-inferiority design (with non-inferiority margins of 10%).Methods and findingsThis randomized controlled trial included children (0.5-10 y) with severe malaria at seven sites in five African countries to assess whether the efficacy of simplified three-dose regimens is non-inferior to a five-dose regimen. We randomly allocated 1,047 children to receive a total dose of 12 mg/kg ARS as either a control regimen of five i.m. injections of 2.4 mg/kg (at 0, 12, 24, 48, and 72 h) (n = 348) or three injections of 4 mg/kg (at 0, 24, and 48 h) either i.m. (n = 348) or i.v. (n = 351), both of which were the intervention arms. The primary endpoint was the proportion of children with ≥ 99% reduction in parasitemia at 24 h from admission values, measured by microscopists who were blinded to the group allocations. Primary analysis was performed on the per-protocol population, which was 96% of the intention-to-treat population. Secondary analyses included an analysis of host and parasite genotypes as risks for prolongation of parasite clearance kinetics, measured every 6 h, and a Kaplan-Meier analysis to compare parasite clearance kinetics between treatment groups. A post hoc analysis was performed for delayed anemia, defined as hemoglobin ≤ 7 g/dl 7 d or more after admission. The per-protocol population was 1,002 children (five-dose i.m.: n = 331; three-dose i.m.: n = 338; three-dose i.v.: n = 333); 139 participants were lost to follow-up. In the three-dose i.m. arm, 265/338 (78%) children had a ≥ 99% reduction in parasitemia at 24 h compared to 263/331 (79%) receiving the five-dose i.m. regimen, showing non-inferiority of the simplified three-dose regimen to the conventional five-dose regimen (95% CI -7, 5; p = 0.02). In the three-dose i.v. arm, 246/333 (74%) children had ≥ 99% reduction in parasitemia at 24 h; hence, non-inferiority of this regimen to the five-dose control regimen was not shown (95% CI -12, 1; p = 0.24). Delayed parasite clearance was associated with the N86YPfmdr1 genotype. In a post hoc analysis, 192/885 (22%) children developed delayed anemia, an adverse event associated with increased leukocyte counts. There was no observed difference in delayed anemia between treatment arms. A potential limitation of the study is its open-label design, although the primary outcome measures were assessed in a blinded manner.ConclusionsA simplified three-dose i.m. regimen for severe malaria in African children is non-inferior to the more complex WHO-recommended regimen. Parenteral ARS is associated with a risk of delayed anemia in African children.Trial registrationPan African Clinical Trials Registry PACTR201102000277177.

The Expanded Programme on Immunisation (EPI) provides an effective way of delivering intermittent preventive treatment for malaria (IPT) to infants. However, it is uncertain how IPT can be delivered most effectively to older children. Therefore, we have compared two approaches to the delivery of IPT to Gambian children: distribution by village health workers (VHWs) or through reproductive and child health (RCH) trekking teams. In rural areas, RCH trekking teams provide most of the health care to children under the age of 5 years in the Infant Welfare Clinic, and provide antenatal care for pregnant women.During the 2006 malaria transmission season, the catchment populations of 26 RCH trekking clinics in The Gambia, each with 400-500 children 6 years of age and under, were randomly allocated to receive IPT from an RCH trekking team or from a VHW. Treatment with a single dose of sulfadoxine pyrimethamine (SP) plus three doses of amodiaquine (AQ) were given at monthly intervals during the malaria transmission season. Morbidity from malaria was monitored passively throughout the malaria transmission season in all children, and a random sample of study children from each cluster was examined at the end of the malaria transmission season. The primary study endpoint was the incidence of malaria. Secondary endpoints included coverage of IPTc, mean haemoglobin (Hb) concentration, and the prevalence of asexual malaria parasitaemia at the end of malaria transmission period. Financial and economic costs associated with the two delivery strategies were collected and incremental cost and effects were compared. A nested case-control study was used to estimate efficacy of IPT treatment courses. Treatment with SP plus AQ was safe and well tolerated. There were 49 cases of malaria with parasitaemia above 5,000/µl in the areas where IPT was delivered through RCH clinics and 21 cases in the areas where IPT was delivered by VHWs, (incidence rates 2.8 and 1.2 per 1,000 child months, respectively, rate difference 1.6 [95% confidence interval (CI) -0.24 to 3.5]). Delivery through VHWs achieved a substantially higher coverage level of three courses of IPT than delivery by RCH trekking teams (74% versus 48%, a difference of 27% [95% CI 16%-38%]). For both methods of delivery, coverage was unrelated to indices of wealth, with similar coverage being achieved in the poorest and wealthiest groups. The prevalence of anaemia was low in both arms of the trial at the end of the transmission season. Efficacy of IPTc against malaria during the month after each treatment course was 87% (95% CI 54%-96%). Delivery of IPTc by VHWs was less costly in both economic and financial terms than delivery through RCH trekking teams, resulting in incremental savings of US$872 and US$1,244 respectively. The annual economic cost of delivering at least the first dose of each course of IPTc was US$3.47 and US$1.63 per child using trekking team and VHWs respectively.In this setting in The Gambia, delivery of IPTc to children 6 years of age and under by VHWs is more effective and less costly than delivery through RCH trekking clinics.ClinicalTrials.gov NCT00376155. Please see later in the article for the Editors' Summary.

BACKGROUND:Presently, many malaria control programmes use health facility data to evaluate the impact of their interventions. Facility-based malaria data, although useful, have problems with completeness, validity and representativeness and reliance on routinely collected health facility data might undermine demonstration of the magnitude of the impact of the recent scaleups of malaria interventions. To determine whether carefully conducted health centre surveys can be reliable means of monitoring area specific malaria epidemiology, we have compared malaria specific indices obtained from surveys in health centres with indices obtained from cross-sectional surveys conducted in their catchment communities. METHODS:A series of age stratified, seasonal, cross-sectional surveys were conducted during the peak malaria transmission season in 2008 and during the following dry season in 2009 in six ecologically diverse areas in The Gambia. Participants were patients who attended the health centres plus a representative sample from the catchment villages of these health facilities. Parasitaemia, anaemia, attributable proportion of fever and anti-MSP1-(19) antibody seroprevalence were compared in the health facility attendees and community participants. RESULTS:A total of 16,230 subjects completed the study; approximately half participated in the health centre surveys and half in the wet season surveys. Data from both the health centre and community surveys showed that malaria endemicity in The Gambia is now low, heterogeneous and seasonal. In the wet season, parasitaemia, seroprevalence and fever prevalence were higher in subjects seen in the health centres than in the community surveys. Age patterns of parasitaemia, attributable proportions of fever and seroprevalence rates were similar in subjects who participated in the community and health centre surveys. CONCLUSION:Health centre surveys have potential as a surveillance tool for evaluating area specific malaria control activities and for monitoring changes in local malaria epidemiology over time.

BACKGROUND:A substantial decline in malaria was reported to have occurred over several years until 2007 in the western part of The Gambia, encouraging consideration of future elimination in this previously highly endemic region. Scale up of interventions has since increased with support from the Global Fund and other donors. METHODOLOGY/PRINCIPAL FINDINGS:We continued to examine laboratory records at four health facilities previously studied and investigated six additional facilities for a 7 year period, adding data from 243,707 slide examinations, to determine trends throughout the country until the end of 2009. We actively detected infections in a community cohort of 800 children living in rural villages throughout the 2008 malaria season, and assayed serological changes in another rural population between 2006 and 2009. Proportions of malaria positive slides declined significantly at all of the 10 health facilities between 2003 (annual mean across all sites, 38.7%) and 2009 (annual mean, 7.9%). Statistical modelling of trends confirmed significant seasonality and decline over time at each facility. Slide positivity was lowest in 2009 at all sites, except two where lowest levels were observed in 2006. Mapping households of cases presenting at the latter sites in 2007-2009 indicated that these were not restricted to a few residual foci. Only 2.8% (22/800) of a rural cohort of children had a malaria episode in the 2008 season, and there was substantial serological decline between 2006 and 2009 in a separate rural area. CONCLUSIONS:Malaria has continued to decline in The Gambia, as indicated by a downward trend in slide positivity at health facilities, and unprecedented low incidence and seroprevalence in community surveys. We recommend intensification of control interventions for several years to further reduce incidence, prior to considering an elimination programme.

In malaria endemic countries, children who have experienced an episode of severe anaemia are at increased risk of a recurrence of anaemia. There is a need to find ways of protecting these at risk children from malaria and chemoprevention offers a potential way of achieving this objective.During the 2003 and 2004 malaria transmission seasons, 1200 Gambian children with moderate or severe anaemia (Hb concentration

Malaria is a risk factor for invasive non-typhoidal Salmonella (NTS) infection in children. In the last 10 years, indices of malaria infection in The Gambia have fallen substantially.We compared temporal trends of childhood malaria and NTS infection in two Gambian locations. In Fajara, on the coast, the incidence of NTS infection at three time points between 1979 and 2005 was compared to the percentage of malaria positive outpatient thick blood films and the percentage of admissions associated with malaria over time. In Basse, in the eastern part of the country, the incidence of NTS infection at three time points between 1989 and 2008 was compared to the prevalence of malaria parasitaemia at four time points between 1992 and 2008.The estimated incidence of NTS infection in Fajara fell from 60 (1979-1984) to 10 (2003-05) cases per 100,000 person years. The proportion of outpatients in Fajara with suspected malaria who were parasitaemic fell from 33% (1999) to 6% (2007) while the proportion of admissions associated with malaria fell from 14.5% (1999) to 5% (2007). In Basse, the estimated incidence of NTS infection fell from 105 (1989-1991) to 29 (2008) cases per 100,000 person years while the prevalence of malaria parasitaemia fell from 45% (1992) to 10% (2008). The incidence of pneumococcal bacteraemia in Fajara and Basse did not fall over the study period.These data support an association between malaria and NTS infection. Reductions in malaria infection may be associated with reduced rates of invasive childhood NTS infection.