Characterisation of the host response to Plasmodium falciparum infection in acute non-complicated malaria.

In this study we have examined serum from patients with Plasmodium falciparum malaria, collected at the time of acute attack and 14 days later. We have also examined sequential samples of sera taken from children living in Madang Province, Papua New Guinea, an area endemic for malaria. The total amount of antibody directed against P. falciparum in acute phase sera was less than that found in matched controls. An in vitro assay measuring inhibition of penetration of uninfected erythrocytes by merozoites of P. falciparum revealed less inhibitory activity in acute phase sera than in matched controls. The longitudinal study of sera from village children demonstrated that non-specific inhibition of intracellular parasite growth was fairly stable, while merozoite inhibiting activity was unstable and varied with time. A cloned P. falciparum species has been used to directly demonstrate the specific growth enhancement by serum in vitro.