Deforestation Clears Way for Zoonotic Malaria in Malaysia
Deforestation Clears Way for Zoonotic Malaria in Malaysia Intensive deforestation in Malaysia's rainforests is exposing more humans to a type of malaria previously found only in long tail and pigtail macaques, report an international team of investigators (Fornace KM et al. Emerg Infect Dis. 2016;22[2]:201 209) An increase in the number of human infections with the zoonotic malaria species Plasmodium knowlesi have been noted in Malaysian Borneo over the last decade, and it is now the leading cause of human malaria in the region. Deforestation has been suggested to drive this emergence by promoting closer contact between humans and mosquitoes that bear the pathogen primarily Anopheles leucosphyrus mosquitoes through spatial overlap between villages and macaques living in nearby forests. To explore potential associations between disease transmission and deforestation, the researchers analyzed data on P knowlesi malaria incidence from health clinics in the districts of Kudat and Kota Marudu in northwestern Sabah, Malaysia, on the island of Borneo from 2008 to 2012. During this time period, they found 2006 people with malaria in 405 villages, of whom 739 were estimated to be infected with P knowlesi. Estimates from remote sensing data indicated a 4.8% concomitant decline in forest cover in Kudat and Kota Marudu. The researchers found during their 5 year period of observation that substantial environmental change occurred in these districts, with 206 of 405 villages (51% having lost more than 10% of forest cover within a 5 km radius. They noted that a higher incidence of P knowlesi across villages was associated with a high rate of forest loss surrounding these villages 5 years before, but not within the same year, the incidence of P knowlesi malaria was reported.