Antibodies to sporozoites: their frequent occurrence in individuals living in an area of hyperendemic malaria.

Serum samples from 158 West Africans were tested for antibodies against sporozoites, the vector stage of the malaria parasite. Antibodies specific for Plasmodium falciparum sporozoites were detected by means of the circumsporozoite precipitation assay and indirect immunofluorescence. More than 90 percent of the serum samples from adults gave positive immunofluorescent reactions against falciparum sporozoites, whereas most of the samples from children gave low or negative reactions.