Deforestation and Monkey Malaria in Malaysia
Scientists believe that deforestation in Malaysia may have indirectly caused a rapid rise in human cases of monkey malaria, most prominently Plasmodium knowlesi, which is usually seen in wild macaque monkeys. Although only the occasional occurrence of P. knowlesi malaria has been reported in the past, widespread deforestation and other agricultural expansion have likely resulted in the disease becoming the most common form of human malaria in many areas of Malaysia.
Monkey malaria was first discovered in the early 1900s, but cases of monkey malaria infecting humans was extremely rare until the last two decades. Since 2008, Malaysia has reported over 15,000 cases of infection and around 50 deaths due to P. knowlesi. Another form of monkey malaria, known as P. cynomolgi, has resulted in the infection of 19 travelers to Southeast Asia this year.
Researchers and scientists believe that the rise of monkey malaria is likely due to deforestation, observing that people most frequently infected with P. knowlesi are those who live or work near deforested land. Kimberly Fornace, an epidemiologist at the London School of Hygiene and Tropical Medicine, insists that certain deforestation initiatives have forced locals into close contact with wild monkeys due to a shared environment.
Fornace pointed out that in Sabah and Sarawak, jungles have been destroyed to make room for oil palm plantations, and workers on those plantations have to work alongside displaced infected monkeys. This is especially dangerous since malaria is a disease that could be easily transferred with the bite of a mosquito.
“P. knowlesi is a really good example of how a disease can emerge and change [as land use changes],” suggests Fornace. She recommends that when big projects are being evaluated for ecological impacts, human health should also be taken into consideration.