Seasonal variation and high multiplicity of first Plasmodium falciparum infections in children from a holoendemic area in Ghana, West Africa.

OBJECTIVE

To assess the prevalence and multiplicity of Plasmodium falciparum infections in Ghanaian infants.

METHOD

In an epidemiological study in an area holoendemic for malaria in Ghana, the prevalence and multiplicity of P. falciparum infections (MOI) were assessed in 1069 three month-old infants by typing of the genes encoding the merozoite surface proteins 1 and 2 (msp-1, msp-2) over a recruitment period of one year. Alleles were amplified using allele family-specific polymerase chain reaction (PCR) assays and determined according to their length polymorphisms on a genetic analyzer.

RESULTS

The occurrence of early infections was dependent on the season (month-stratified prevalence 6.4-29.0%). Diversity of msp-alleles was extensive and significantly higher in the dry than in the rainy season.

CONCLUSIONS

The level of infection prevalence and the high multiplicity of infections (median 4, maximum 14 strains per isolate) in the first months of life indicate early contacts with parasites exhibiting a wide repertoire of antigens and, most likely, multiple infections per single mosquito bite.