Malaria and Hepatocystis species in wild macaques, southern Thailand.
ABSTRACT Southeast Asian macaques are natural hosts for a number of nonhuman primate malaria parasites; some of these can cause diseases in humans. We conducted a cross-sectional survey by collecting 99 blood samples from Macaca fascicularis in southern Thailand. Giemsa-stained blood films showed five (5.1%) positive samples and six (6.1%) isolates had positive test results by polymerase chain reaction. A phylogenetic tree inferred from the A-type sequences of the small subunit ribosomal RNA gene confirmed Plasmodium inui in five macaques; one of these macaques was co-infected with P. coatneyi. Hepatocystis, a hemoprotozoan parasite transmitted by Culicoides, was identified in an isolate that was confirmed by analysis of mitochondrial cytochrome b sequences. All malaria-infected monkeys lived in mangrove forests, but no infected monkeys were found in an urban area. These findings indicate regional differences in malaria distribution among these macaques, as well as differences in potential risk of disease transmission to humans.
Article: Malaria zoonoses.[show abstract] [hide abstract]
ABSTRACT: The genus Plasmodium includes many species that naturally cause malaria among apes and monkeys. The 2004 discovery of people infected by Plasmodium knowlesi in Malaysian Borneo alerted to the potential for non-human species of plasmodia to cause human morbidity and mortality. Subsequent work revealed what appears to be a surprisingly high risk of infection and relatively severe disease, including among travelers to Southeast Asia. The biology and medicine of this zoonosis is reviewed here, along with an examination of the spectrum of Plasmodium species that may cause infection of humans.Travel Medicine and Infectious Disease 09/2009; 7(5):269-77. · 1.50 Impact Factor
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ABSTRACT: Since a large focus of human infection with Plasmodium knowlesi, a simian malaria parasite naturally found in long-tailed and pig tailed macaques, was reported in Sarawak, Malaysian Borneo, it was pertinent to study the situation in peninsular Malaysia. A study was thus initiated to screen human cases of Plasmodium malariae using molecular techniques, to determine the presence of P. knowlesi in non- human primates and to elucidate its vectors. Nested polymerase chain reaction (PCR) was used to identify all Plasmodium species present in the human blood samples sent to the Parasitology laboratory of Institute for Medical Research. At the same time, non-human primates were also screened for malaria parasites and nested PCR was carried out to determine the presence of P. knowlesi. Mosquitoes were collected from Pahang by human landing collection and monkey-baited-traps situated on three different levels. All mosquitoes were identified and salivary glands and midguts of anopheline mosquitoes were dissected to determine the presence of malaria parasites and nested PCR was carried out on positive glands. Sequencing of the csp genes were carried on P. knowlesi samples from humans, monkeys and mosquitoes, positive by PCR. Plasmodium knowlesi was detected in 77 (69.37%) of the 111 human samples, 10 (6.90%) of the 145 monkey blood and in 2 (1.7%) Anopheles cracens. Sequence of the csp gene clustered with other P. knowlesi isolates. Human infection with Plasmodium knowlesi is occurring in most states of peninsular Malaysia. An. cracens is the main vector. Economic exploitation of the forest is perhaps bringing monkeys, mosquitoes and humans into increased contact. A single bite from a mosquito infected with P. knowlesi is sufficient to introduce the parasite to humans. Thus, this zoonotic transmission has to be considered in the future planning of malaria control.Parasites & Vectors 02/2008; 1(1):26. · 2.94 Impact Factor
Article: Knowlesi malaria in Vietnam.[show abstract] [hide abstract]
ABSTRACT: The simian malaria parasite Plasmodium knowlesi is transmitted in the forests of Southeast Asia. Symptomatic zoonotic knowlesi malaria in humans is widespread in the region and is associated with a history of spending time in the jungle. However, there are many settings where knowlesi transmission to humans would be expected but is not found. A recent report on the Ra-glai population of southern central Vietnam is taken as an example to help explain why this may be so.Malaria Journal 11/2009; 8:269. · 3.19 Impact Factor