Monkey malaria more widespread in humans

A potentially fatal type of malaria is being commonly misdiagnosed as a more benign form of the disease, putting people at risk, researchers in Malaysia say.

Malaria parasite Plasmodium knowlesi was until recently thought to infect only monkeys, especially long and pig-tailed macaques that are its natural hosts.

But a study of samples taken from more than 1,000 malaria patients in Malaysia between 2001 and 2006 found that the disease was more widespread in humans than previously thought.

Four of those infected, all from Sarawak, died.

More than a quarter of the patients in Sarawak, on Malaysia's part of Borneo island, were infected with Plasmodium knowlesi, the researchers wrote in the latest issue of Clinical Infectious Diseases journal. A total of 960 of the patients in the sample group were from Sarawak.

"Our finding that P. knowlesi and not P. malariae (benign species) is a significant cause of potentially severe malaria in Malaysia and has important implications for clinical management and control strategies in the local setting, as well as for physicians attending patients," they wrote.

Blood of the four dead patients had high levels of parasites and they had suffered severe abdominal pain, fever and chills.

The researchers said even a short delay in accurate diagnosis and treatment could lead to the rapid onset of complications, including liver and kidney failure.

The parasite is transmitted by a family of mosquitoes that is attracted equally to monkeys and humans. The researchers say the disease is not only restricted to Sarawak, but was present in Sabah, also in Borneo, and Pahang in peninsular Malaysia.