Factors determining the true reservoir of infection of Plasmodium falciparum and Wuchereria bancrofti in a West African village

Abstract

Field tests indicate that 25% of infective carriers of Plasmodium falciparum are cryptic carriers (blood smears frequently almost negative for crescents). About 10% of those carrying abundant crescents (especially true of infants) are non-infective to mosquitoes (A. gambiae and A. funestus). Children of 2-9 are probably the best inf ectors of mosquitoes, although adults may play a more important role than is usually considered. Tests showed that nearly one-third of the adult natives may be infective with Wuchereria bancrofti microfilariae. They are most infective between 8 P. M. and 4. A. M. (sleep time) at which period A. gambiae is also most active. In general, the older the native, the better chance of infecting mosquitoes. A. gambiae, because of its longer life span, is a better vector than A. funestus, since more opportunity for reaching the salivary glands is afforded. Both species of mosquitoes are carriers of falciparum malaria and of bancroftian filariasis.