23 May 2024

Officials from Thailand’s Department of National Parks, Wildlife and Plant Conservation and the Department of Livestock Development have been sent to Chang Island in Trat province to collect blood samples from wild and domesticated monkeys, to be tested for Plasmodium knowlesi, a parasite that causes malaria in monkeys and other primates, after nine people on the island were found to be infected.

Two other human cases were found in the Bo Rai district of the same province.

In March, blood samples from eight wild and domesticated long-tailed macaque were sent to the lab of the Department of Disease Control for analysis. Two of the samples tested positive for Plasmodium falciparum.

According to health officials, monkey malaria can be transmitted to humans by bites from striped mosquitoes which are infected with the parasite. So far, however, there have been no reports of human-to-human transmission.

Monkey malaria was declared an emerging disease in Thailand in 2004. Each year, usually about 10 cases are reported but, since late last year, about 100 cases have been reported and one person has died in Songkhla province. Most cases were found in Ranong, Songkhla and Trat provinces, especially along the country’s borders.