Molecular Characterisation and Immuno - Epidemiology of Plasmodium Falciparum Infection in School Children at Dodowa

Abstract

A longitudinal immuno-epidcmiological study was conducted between April 1994 and August 1995 among Ghanaian children within the ages of 3-15 years, living in Dodowa, a stable malaria endemic area. A polymerase chain reaction (P C R ) typing technique based on the amplification of polymorphic region of merozoite surface protein 1 (M S P 1 ) of Plasmodium falciparum gene, was used to characterise parasites contained in blood spotted filter paper. The PC R assay detected as low as 2.2 parasites/^! of blood and revealed 35 MSP1 seasonally variable allelic forms in the children. Clinical malaria could not be attributed to any specific allelic tvpe, and the acquisition of new allelic type was not necessarily associated with clinical malaria. Malaria episode was synchronised with significant increase in parasitaemia. Also anti-MSPl|y antibodies were measured using Enzyme-linked immunosorbent assay (EL.1SA) from blood samples collected from 27 of these children before and after malaria attack, \niibody responses to the C'-terminal of l9kDa fragment of Plasmodium falciparum before malaria attack showed 14 children as positive and 13 negati\e. Nine of the children were within the ages of 3-4 years whereas eighteen were 5 years and above. Four children out of the nine aged 3-4 years were negative before malaria attack but three showed negative to positi\e sero-conversion. In contrast 2 out of 9 children who were positive before malaria attack showed positive to negative sero-conversion.