Monkey malaria infects and kills humans also

KUALA LUMPUR - A parasite suspected to infect monkeys is now the fifth most common cause of malaria in humans, a new study says.

Malaria kills more than a million people each year. It is caused by malaria parasites which are injected into the bloodstream by infected mosquitoes.

Of the four species of malaria that commonly cause disease in humans, Plasmodium falciparum found most commonly in Africa is the most deadly.

P. malariae found in tropical and sub-tropical regions across the globe has symptoms that are usually less serious.

Recently, researchers at the University Malaysia Sarawak, led by Balbir Singh and Janet Cox-Singh, showed that P. knowlesi, a malaria parasite that infected monkeys, particularly long or pig-tailed macaques, also infects humans in Malaysia.

Subsequent reports in neighbouring Southeast Asian countries have led to the recognition of P. knowlesi as the fifth cause of malaria in humans.

Singh and Cox-Singh, with colleagues from University of Western Australia, have published the first detailed prospective study of the clinical and lab features of human P. knowlesi infections.

“P. knowlesi malaria can easily be confused with P. malariae since these two parasites look similar by microscopy, but the latter causes a benign form of malaria,” says Singh, according to a university statement.

“In fact, because the P. knowlesi parasites reproduce every 24 hours in the blood, the disease can be potentially fatal, so early diagnosis and appropriate treatment is essential.”

Researchers initially recruited over 150 patients admitted to Kapit Hospital in Sarawak, Malaysian Borneo, between July 2006 and January 2008 who had tested positive with a blood film slide for Plasmodium species.

The study was published in Clinical Infectious Diseases.