Plasmodium coatneyi: Observations on periodicity, mosquito infection, and transmission to Macaca mulatta monkeys

Plasmodium coatneyi has adapted well to experimental studies with Macaca mu latta monkeys and Anopheles dirus mosquitoes. Studies were made to determin e 1) the course of asexual parasitemia, 2) periods when infective gametocyt es were produced, 3) the laboratory-reared mosquitoes susceptible to infect ion, 4) the mosquito most capable of transmitting the infection to monkeys via bite, 5) the pattern of recrudescence, and 6) the prepatent periods fol lowing the bites of infected An. dirus mosquitoes. The period when infectiv e gametocytes. are produced is concentrated primarily in the first week whe n parasitemia exceeds 1,000/mul. Mosquitoes were more heavily infected on d ays when the asexual parasite counts were highest. Gametocyte counts were g enerally low. Mature forms of the parasite markedly sequestered giving a pa ttern of high-low periodicity. Anopheles dirus and An. freeborni mosquitoes were nearly equal in terms of their ability to support oocyst development. Other species (An. stephensi, An. maculatus, and An. gambiae,) were less s upportive. High sporozoite densities in the salivary glands were frequently produced in An. dirus and sporozoite transmission was obtained via the bit es of these mosquitoes after 12-18 days of extrinsic incubation. Prepatent periods ranged from 10 to 15 days. The presence of frequent parasitic recru descences suggests mechanisms similar to that seen in human infections with P, falciparum. It is proposed that P. coatneyi in M. mulatta monkeys can b e a suitable model for studies on cerebral pathology, vaccine efficacy, and the testing of antimalarial drugs.