10:21am

Wed February 6, 2013
Science

Who Carries More Disease, Bats Or Rats? A New CSU Study Knows

A new study by Colorado State University says while rodents vastly outnumber bats, the small flying creatures are more likely to carry viruses transmittable to humans then their ground scurrying counterparts.

The study was authored by CSU Professor of Biology Colleen Webb and Postdoctoral Fellow Angela Luis. Luis says there’s something special about bats and the number of deadly zoonotic diseases they carry.

“We found that although there are twice as many rodent species as there are bat species, bats hosted more zoonotic viruses per species than rodents.”

What are zoonotic diseases you ask? They’re diseases that can be transmitted between an animal and a human like SARS and Ebola as well as some strains of the flu.

What’s more, the study finds bats are more likely to pass those deadlier viruses between different bat species easier then rodents. “We found the most important factor that was correlated to hosting more viruses for both bats and rodents was the number of other species within its geographic range.” Luis says while true for rodents, “we found that with bats, the effect was four times stronger.”

Luis says her work suggests viruses may pass more easily or quickly between different bat species than between rodent species, but rodents still carry a significant number of viruses deadly to humans.

“A lot of these really nasty bat viruses that we’re concerned with, like the ones that I mentioned SARS Ebola, Nipah, and Hendra are very deadly but there actually haven’t been that many infections.”

The study funded by Research and Policy for Infectious Disease Dynamics, or RAPIDD, through the National Institutes of Health Fogarty International Center and the U.S. Department of Homeland Security, is important because it shows that bats are indeed capable of hosting more viruses very deadly to humans, and according to Luis that highlights the importance of minimizing human and bat contact.

For example, with deforestation in Malaysia humans moved into bat populated areas and pig farms and orchards replaced bat habitats. Luis says infected bats roosted in the orchards and ate the fruit, dropping pieces of the virus filled fruit on the ground. Pigs in turn ate that fruit and spread the viruses to humans.

Even though bats are special as far as hosting nasty diseases like Ebola and SARS, they’re really important ecologically. Luis says bats eat enough insects to account for as much as $3 billion worth of pesticide control annually in the United States. “We want to promote limiting bat and human contact, which will be beneficial for both bat conservation and human health.”