Sporozoite transmission of three strains of Plasmodium knowlesi to Aotus and Saimiri monkeys.

Attempts were made to infect Aotus and Saimiri monkeys with sporozoites of 3 strains of Plasmodium knowlesi to determine the potential of these animals in a monkey/malaria model. Splenectomized Saimiri and Aotus monkeys were infected with the H strain of P. knowlesi via sporozoites from Anopheles dirus mosquitoes. Prepatent periods ranged from 5 to 16 days. Saimiri monkeys infected with the Philippine strain had prepatent periods ranging from 6 to 8 days. Saimiri monkeys infected with the Hackeri strain had prepatent periods ranging from 6 to 11 days. Exoerythrocytic (EE) stages of the Philippine strain were readily demonstrated; EE stages of the H strain were less abundant. Results indicate that the Philippine strain of P. knowlesi in Saimiri monkeys has a course of parasitemia and EE stages similar to those previously seen in macaques and could serve as a reproducible model for biologic and immunologic studies.