Abstract
BackgroundSeasonal malaria chemoprevention (SMC) consists of administration of sulfadoxine-pyrimethamine (SP) + amodiaquine (AQ) at monthly intervals to children during the malaria transmission period. Whether the addition of azithromycin (AZ) to SMC could potentiate the benefit of the intervention was tested through a double-blind, randomized, placebo-controlled trial. The effect of SMC and the addition of AZ, on malaria transmission and on the life history traits of Anopheles gambiae mosquitoes have been investigated.MethodsThe study included 438 children randomly selected from among participants in the SMC + AZ trial and 198 children from the same area who did not receive chemoprevention. For each participant in the SMC + AZ trial, blood was collected 14 to 21 days post treatment, examined for the presence of malaria sexual and asexual stages and provided as a blood meal to An. gambiae females using a direct membrane-feeding assay.ResultsThe SMC treatment, with or without AZ, significantly reduced the prevalence of asexual Plasmodium falciparum (LRT X22 = 69, P < 0.0001) and the gametocyte prevalence (LRT X22 = 54, P < 0.0001). In addition, the proportion of infectious feeds (LRT X22 = 61, P < 0.0001) and the prevalence of oocysts among exposed mosquitoes (LRT X22 = 22.8, P < 0.001) was reduced when mosquitoes were fed on blood from treated children compared to untreated controls. The addition of AZ to SPAQ was associated with an increased proportion of infectious feeds (LRT X21 = 5.2, P = 0.02), suggesting a significant effect of AZ on gametocyte infectivity. There was a slight negative effect of SPAQ and SPAQ + AZ on mosquito survival compared to mosquitoes fed with blood from control children (LRTX22 = 330, P < 0.0001).ConclusionThis study demonstrates that SMC may contribute to a reduction in human to mosquito transmission of P. falciparum, and the reduced mosquito longevity observed for females fed on treated blood may increase the benefit of this intervention in control of malaria. The addition of AZ to SPAQ in SMC appeared to enhance the infectivity of gametocytes providing further evidence that this combination is not an appropriate intervention.
Highlights
Seasonal malaria chemoprevention (SMC) consists of administration of sulfadoxine-pyrimethamine (SP) + amodiaquine (AQ) at monthly intervals to children during the malaria transmission period
SMC consists of administration of therapeutic doses of sulfadoxine-pyrimethamine (SP) + amodiaquine (AQ) at monthly intervals to children aged 3–59 months during the peak malaria transmission period in areas where malaria transmission is seasonal [2]
These findings indicate that SMC with SPAQ may have an effect on the overall transmission of malaria, especially if SMC was extended to older children, but that addition of AZ will not enhance this effect
Summary
Seasonal malaria chemoprevention (SMC) consists of administration of sulfadoxine-pyrimethamine (SP) + amodiaquine (AQ) at monthly intervals to children during the malaria transmission period. The reduction of malaria burden has stalled, or even reversed, in some countries in the recent years and additional strategies are needed These include chemopreventive strategies such as intermittent preventive treatment during pregnancy (IPTp) and seasonal malaria chemoprevention (SMC) for children [1]. To determine whether the addition of AZ to SMC could reduce child mortality and morbidity was tested through a double-blind, randomized, placebocontrolled trial in young children in Burkina Faso and Mali. This trial showed that the addition of AZ reduced the incidence of several infectious diseases but did not reduce the incidence of deaths or hospital admissions [4]. Addition of AZ to SMC had little effect on the incidence of clinical attacks of malaria, but it may have had some effect on malaria transmission, and determining whether this was the case warrants further attention
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