ABSTRACT

The findings in the sporozoite-immunized rodent and simian hosts were confirmed in human volunteers in the 70's (Clyde et af. , 1 973a,b, 1 975 ; McCarthy and Clyde, 1 977; Rieekmann et al . . 1 979), and more recent studies (Herrington et al. , 1 99 1 ; Egan et al. , 1 993) . In the studies, five volunteers were protected against P. Jalciparum and two volunteers against vivax malaria following exposure to the bites of ir adiated mosquitoes infected with either P Jalciparum or P vivax, respectively. Consistent with the small number of parasites injected per bite, induction of protective immunity required multiple exposures to the bites of numbers of irradiated malaria-infeclcd mosquitoes (a total of 379-440) over a period of time ranging from three to ten months (Clyde et af. , 1 973a,b ; Rieckmann et al. , 1 979). The two volunteers successfully immunized against vivax malaria were exposed seven to ten times to a total of 539-1979 irradiated P. infected mosquitoes (Clyde et aI. , 1 975; McCarthy and 1 977).