Plasmodium fieldi: observations on the Hackeri and ABI strains in Macaca mulatta monkeys and mosquitoes.

Macaca mulatta monkeys infected with the Hackeri strain of Plasmodium fieldi had maximum parasite counts ranging from 1,300 to 301,320/mu L. In 43 intact animals infected with the ABI strain, the maximum parasite counts ranged from 672 to 57,189/mu L (median = 15,100/mu L); in 46 splenectomized monkeys, the maximum parasite count ranged from 660 to 350,000/mu L (median = 52,245/mu L). Transmission through Anopheles dirus Mosquitoes was obtained on I I occasions with pre-patent periods of 9-14 days. Relapses occurred between two and eight times during a 1-year period. P fieldi has potential for testing prophylactic and radical curative drugs.