Courses of infections with Plasmodium falciparum in own monkeys displaying a microfilaremia.

Infections with the Uganda Palo Alto, Malayan Camp-CH/Q, Vietnam Oak Knoll, and Vietnam Smith strains of Plasmodium falciparum in owl monkeys (Aotus trivirgatus griseimembra) with concomitant microfilaremias usually, but not always, followed a more benign course than infections with the same strains in monkeys free of filarial infections. Four distinct microfilariae were identified in systematic examinations of 26 monkeys, 5 with self-limited infections with P. falciparum, 9 with normally benign self-limited infections with P. vivax, and 12 without previous malaria. The microfilariae found included: Dipetalonema (Dipetalonema) gracile, Tetrapetalonema (Tetrapetalonema) barbascalensis, T. (T.) panamensis, and an unidentified species designated "Aotus C." Among 23 monkeys studied completely, 14 were infected with a single species, 4 had double infections, and 5 had triple infections. T. barbascalensis was identified in 16 monkeys, T. panamensis in 11. Although data were very limited, there was a suggestion that infections with P. falciparum were less intense in monkeys infected with T. barbascalensis, either alone or with other filariae, than in subjects infected only with T. panamensis.