The Influence of Splenectomy on Infections of Plasmodium fieldi in Macaca mulatta Monkeys

Abstract

The parasitemias, IFA responses, and mosquito infection levels in intact and splenectomized Macaca mulatta monkeys and Anopheles freeborni mosquitoes infected with Plasmodium fieldi were de- termined for a 35-day period of observation following inoculation. Splenectomy prior to inoculation resulted in the greatest increase in parasitemias and mosquito infection levels. In those monkeys splenectomized 12 to 13 days following inoculation, parasitemias and particularly mosquito infections were increased markedly over those of intact animals. Splenectomy is a standard procedure for in- creasing the level of parasitemia in monkeys infected with the monkey malarias. The pres- ent report deals with the effect of splenectomy on (1) the course of the parasitemia, (2) the infectivity to susceptible mosquitoes, and (3) the changes in the antibody response of the host as measured by the indirect fluorescent antibody (IFA) technique. Animals were in- fected with Plasmodium fieldi, a species of monkey malaria which normally produces a low level of parasitemia and which seldom endangers the well-being of the host.