Drug resistance maps to guide intermittent preventive treatment of malaria in African infants

Intermittent preventive treatment of infants (IPTi) with sulphadoxine pyrimethamine (SP) is recommended as an additional malaria control intervention in high transmission areas of sub-Saharan Africa, provided its protective efficacy is not compromised by SP resistance. A significant obstacle in implementing SP-IPTi, is in establishing the degree of resistance in an area. Since SP monotherapy is discontinued, no contemporary measures of in vivo efficacy can be made, so the World Health Organisation has recommended a cut-off based upon molecular markers, stating that SP-IPTi should not be implemented when the prevalence of the dhps 540E mutation among infections exceeds 50%. We created a geo-referenced database of SP resistance markers in Africa from published literature. By selecting surveys of malaria infected blood samples conducted since 2004 we have mapped the contemporary prevalence of dhps 540E. Additional maps are freely available in interactive form at http://www.drugresistancemaps.org/ipti/. Eight countries in East Africa are classified as unsuitable for SP-IPTi when data are considered at a national level. Fourteen countries in Central and West Africa were classified as suitable while seven countries had no available contemporary data to guide policy. There are clear deficiencies in molecular surveillance data coverage. We discuss requirements for ongoing surveillance of SP resistance markers in support of the use of SP-IPTi.