Epidemiology of malaria in a village of Sudanese savannah in Mali (Bancoumana). Anti-TRAP and anti-CS humoral immunity response

Vaccine development research is an important component of malaria control strategies. Thrombospondin related anonymous protein (TRAP) and the circumsporozoite (CS) protein are two antigens of sporozoite surface. Immune response to these two antigens may contribute to the development of anti-sporozoite vaccine. Recent studies suggest that antibodies anti-TRAP may partially block sporozoites penetration in hepatocyte, and thereby reducing malaria morbidity. We carried out a study to assess the seroprevalence of anti-TRAP and anti-CS antibodies and to identify a possible role of these antibodies on malaria morbidity in children 1-9 years old living in a rural hyperendemic village. We performed 5 cross sectional surveys and a longitudinal follow up in 1993 and 1994. During each cross sectional study, children were examined for fever and splenomegaly; all febrile children received thick film examination, and serologic analysis was performed in one third of these, randomly selected. The results show that the seroprevalence of anti-TRAP and anti-CS varied with age and season (p < 0.05). Association between the prevalence of anti-TRAP and splenomegaly was observed during two cross sectional surveys (June and October 1993). The presence of anti-TRAP antibody was associated with Plasmodium falciparum infection at the beginning of the transmission season (June 1993 and July 1994). A negative association between the level of anti-TRAP title and parasitemia was observed (March and October 1994). These findings suggest no clear evidence of the protective role of anti-TRAP antibodies in uncomplicated malaria, possibly due to the limited persistence of these antibodies under natural situations.