By James Gallagher, BBC
Scientists are warning that a species of malaria could switch from targeting monkeys to humans.
Macaques in south east Asia are a vast source of Plasmodium knowlesi which can spread to people, they write in PLoS Pathogens.
They believe that growing human populations and increased deforestation in the region could lead to the parasite switching host.
But those changes could also reduce the spread of the disease.
Around one million people die each year as a result of malaria.
It is caused by parasites and is spread by mosquitoes when they drink blood.
Read more here.