Advance 3: Chemoprevention in malaria endemic areas
For many years pregnant women living in a malaria endemic region were advised to take chloroquine chemoprophylaxis to reduce the adverse effects of falciparum malaria on the developing foetus (mainly low birthweight), but as chloroquine resistance worsened chemoprophylaxis was replaced by intermittent presumptive treatment with sulphadoxine-pyrimethamine (IPT-SP) (1). This involves giving full treatment doses at intervals. Although preventive efficacy is much greater than treatment efficacy against resistant P. falciparum , IPT-SP is threatened by worsening resistance – both to the antifol and the sulphonamide components (28). There is increasing evidence that dihydroartemisinin-piperaquine (DP) provides excellent antimalarial chemoprevention for approximately one month, is well tolerated, and appears safe in pregnancy (29, 30). IPT is imperfect chemoprophylaxis. In order to provide continuous suppressive prophylaxis DP needs to be given at least monthly, and preferably weekly (31). The IPT-SP concept has also been advocated in infants, where treatment doses of SP are to be given together with the routine EPI vaccines at the ages of 2, 3 and 9 months. This is not widely practiced as the benefits are relatively small, and SP resistance is widespread. A more effective strategy, which is now implemented widely across the Sahel region of Africa (where there is intense malaria transmission largely confined to the 3-4 month rainy season), is seasonal malaria chemoprevention (SMC) with monthly administration of treatment doses of amodiaquine together with SP to all children aged between 6 and 59 months (1, 32). SMC prevents symptomatic reinfection and substantially reduces the malaria burden. Adding azithromycin to amodiaquine and SP provides no additional benefit (33). Resistance to both components of SMC is widespread in East Africa but whether resistance is impacting on the chemoprophylactic activity of SMC is uncertain currently – more information is needed on this critical point to guide policy.