With the recent global outbreaks of Zika and Ebola, have you ever wondered if we can predict the next one? And where in the world it will come from? Me too. Predicting the next zoonotic outbreak is not easy, however a study recently published in Nature aims to do just that.
EcoHealth Alliance, the organization that lead the study, looked at mammals, the viruses they carry, and how those animals come into contact with humans. Researchers made a list of all known viruses in mammals and came up with 586 viruses that infect 754 species of mammals. These 586 viruses includes 188 known zoonotic viruses, ones that have already infected mammals and humans.
Unsurprisingly to many folks, bats, primates and rodents carry the largest proportion of zoonotic viruses. The researchers estimate that each species of bat carries 17 different viruses while each species of primate and rodent carry 10.
Additionally, there are two factors that boost the chances that an animal will transmit a virus to people: how closely related the animal is to humans (phylogenetically) and how much time the animal spends in urban areas. And finally, the more species the virus infects the more likely it is to end up infecting humans. Now you can start to see why we should care so much about zoonotic infections.
Now that the researchers had this information about how likely viruses were to move from mammals to humans, they used it to predict the “hotspots” where we might find novel zoonotic viruses.
Basically the entire world’s population is at risk of these potential zoonoses, in some form or another. The risk from bats was global but concentrated in South America. The threat from primates was primarily in the tropical regions of the world. The rodent threat was concentrated in North and South America, and parts of Central America.
I’m not trying to be an alarmist here. The maps show the risk, not the zoonoses that will actually happen. The goal of this study was to help people plan effective surveillance efforts by focusing on the identified hotspots, and for communities to keep this information in mind when they expand into the habitat of nearby animals.
We may never be able to truly predict the next major global zoonotic outbreak, but studies like these give us an idea of what we’re up against and where we should focus our resources so we can catch the next outbreak right when it starts.