The H strain of P. knowlesi was transmitted through the bites of Anopheles balabacencis balabacensis mosquitoes from monkey to man, from man to man, and from man back to monkey. All attempts to infect man through the bites of infected mosquitoes were successful, one volunteer contracting infection after only a single infective bite. The prepatent periods in man ranged from 9 to 12 days, and in the monkey was 6 days. The infections exhibited a quotidian periodicity, and were characterized by relatively high parasitemia and moderate to severe clinical manifestations.
The significance of this zoonosis as it may affect a program of malaria eradication is discussed.
Present address: National Communicable Disease Center, Eradication Program, Evaluation Section, 1600 Clifton Road, Atlanta, Georgia 30333.