Plasmodium inui, a Quartan-Type Malaria Parasite of Old World Monkeys Transmissible to Man

Abstract

A quartan-type parasite of Old World monkeys has been found infective to man by the bites of infected mosquitoes (Anopheles stephensi and/or A. maculatus) in two volunteers and by the inoculation of parasitized blood in five volunteers. The prepatent period in the sporozoite-induced infections was 31 and 56 days with parasitemia for 21 and 24 days, respectively. The blood-induced infections were patent for 10 to 26 days. A quartan fever pattern was well marked in two volunteers with maximum fever of 103.2 F. The incidence of chills was low. Parasitized blood from four of the volunteers when injected into clean rhesus monkeys produced typical infections. In 1960 Eyles et al. reported the first natural transmission of a simian malaria to man which occurred accidentally with the B strain of Plasmodium cynomolgi, a tertian-type parasite. This was followed shortly by the transmission of other strains of the same species by Coatney et al. (1961), Schmidt et al. (1961), and later by Bennett and Warren (1965). Contacos et al. (1963) transmitted P. brasilianum, a quartan-type parasite of New World monkeys, to man by the bites of infected mosquitoes. Chin et al. (1965) reported the first recognized transmission of P. knowlesi to man in nature. In addition, these authors were able to infect rhesus monkeys by the inoculation of sporozoites obtained from mosquitoes which became infected after feeding