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.