Deadly viruses that cause panic and epidemics are becoming more common because of deforestation the depletion of natural habitats for wild animals.

The deadly viruses themselves aren't increasing, it’s their exposure to humans that has increased. As humans trek further into the forests and environments where viruses like Ebola, Zika, and HIV are common among bats, rodents, and other animals, the higher the chances are that those viruses will make the jump to infecting humans, according to NPR.

The way humans have changed the environment has led to increased exposure to such viruses, and not just in places like the rainforest, Kevin Olival, a virus hunter and researcher with EcoHealth Alliance, told NPR. Even development in the suburbs and in cities can cause an increase in such viruses because animals are pushed into environments where they come in closer contact with people.  

NPR caught up with Olival in the Malaysian rainforest where palm tree forests have been devastated by the demand for palm oil. Other parts of the world have seen a similar trend, where high demand for a product has altered the landscape. Whether it be a demand for more housing, palm oil or soy beans, the areas impacted are being ravaged of more than just their natural resources. The viruses that thrive among the dense vegetation and animal populations come with collecting those resources as well.

Olival is working as part of PREDICT, a United States Agency for International Development project, to find the next potentially devastating virus before it has a chance to becoming the next epidemic. So far, PREDICT has identified 820 novel viruses and 120 known viruses through sampling more than 74,000 people and animals in high risk areas to help better prepare for future outbreaks. The hope is that in an effort to avoid the next outbreak, such research is, “improving global disease recognition and beginning to develop strategies and policy recommendations to minimize pandemic risk,” says to PREDICT’s website.

The viruses coming from these areas vary in severity but infect, and sometimes kill, large groups of people. During the Ebola outbreak between 2014 and 2016, of the nearly 27,000 people who were infected more than 11,000 died, according to CDC data. And in the United States and its territories alone more than 40,000 cases of Zika have been reported, though the disease is mostly a threat to pregnant women and young children and many adults experience only mild symptoms if any at all.