A Naturally Acquired Quotidian-Type Malaria in Man Transferable to Monkeys

Abstract

A quotidian-type parasite, Plasmodium knowlesi, has been found as a ndtural infection in man. The infection was acquired by a white male during a short visit to peninsular Malaysia. This occurrence constitutes the first proof that simian malaria is a true zoonosis.In 1960 the tertian-type simian parasite, Plasmodium cynomolgi, B strain (1), was accidentally transferred to man by mosquito bite (2). Shortly thereafter, other strains of the same species were shown to be infective to man by the same route (3). In 1963 the quartan-type parasite of New World monkeys, P. brasilianum, was also shown to be infective to man as a result of bites of infected mosquitoes (4). Until this present report, none of the simian malarias have been found as natural infections in man.A 37-year-old white male, B.W., a surveyor for the U.S. Army Map Service, was admitted to the Clinical Center of the National Institutes of Health on 9 April 1965 with complaints of chills, fever, and sweating of several days' duration. His illness began 9 days prior to admission when he was in Bangkok, having returned from 4 weeks in Malaya. At this time he experienced anorexia, mild fatigue, and occasional nausea. Because his symptoms were not severe, he elected to return to the U.S. before seeking medical attention. Three days prior to his admission, the patient had arrived at Travis Air Force Base in California, where he experienced sore throat and shaking chills, associated with high fever and profuse sweating. He was seen by the base physician who treated him for an upper respiratory infection, whereupon he proceeded to his home in Silver Spring, Maryland. There he was seen by his private physician during a chill. Upon finding many ring-form parasites in a smear from the patient's peripheral blood, the physician made a tentative diagnosis of falciparum malaria. The patient was then referred to the Clinical Center at the National Institutes of Health, where the diagnosis of malaria wlas A Naturally Acquired Quotidian-Type Malaria in Man Transferable to MonkeysAbstract. A quotidian-type parasite, Plasmodium knowlesi, has been found as a ndtural infection in man. The infection was acquired by a white male during a short visit to peninsular Malaysia. This occurrence constitutes the first proof that simian malaria is a true zoonosis.

A monkey's tale: The origin of Plasmodium vivax as a human malaria parasite

“…A host switch from Macaca sp. to Homo is readily possible and has been demonstrated by natural infections in modern humans with P. knowlesi under circumstances of natural transmission in mainland Malaysia and Borneo (41,42). In addition, it has been postulated that P. simiovale may be found in humans, although the data available is from a single gene (43,44).…”

Meager genetic variability of the human malaria agent Plasmodium vivax

“…Lateral transmission of Plasmodium parasites from monkey hosts to humans is known for several species, including P. simium (50), Plasmodium brasilianum (51), P. cynomolgi (52), P. knowlesi (53), and perhaps Plasmodium simiovale (54). Transmission from humans to monkeys can be accomplished experimentally (53) and may also occur naturally (55).…”

“…Transmission from humans to monkeys can be accomplished experimentally (53) and may also occur naturally (55).…”

Centenary celebrations article

“…The earliest report of a confirmed natural infection of P. knowlesi in humans was in 1965 in a US traveler who spent a few weeks in a forest of Pahang, Peninsular Malaysia (Chin et al 1965). Initially this case was microscopically identified as P. falciparum and the next day as P. malariae, and later it was confirmed as P. knowlesi from the inoculation of infected blood into rhesus monkeys.…”

“…However, P. knowlesi infections in humans were soon discontinued as the infections became uncontrollable and life threatening and treatment of neurosyphilis patients was resumed with P. vivax infections which were at that time considered totally benign. P. knowlesi was found naturally infecting man in 1961 (Chin et al 1965). With the reporting of a large focus of this infection in humans in Malaysian Borneo (Singh et al 2004), and subsequent finding of this parasite in several countries in South-east Asia, this parasite was recognized as the fifth human malaria parasite (White 2008).…”