Bats Provide Key Link in Undiscovered Disease Detection

Scientists are investigating possible connections between bats and the transmission of infectious diseases to determine if bats play a role in spreading diseases that affect human health. Although bats are carriers of rabies, a lack of research has prevented scientists from drawing conclusions about connections between the flying mammal and other diseases.

To begin researching possible connections between bats and human health problems, Tony Goldberg, PhD, professor of pathobiological sciences at the University of Wisconsin-Madison, and colleagues analyzed the relationship between an African forest bat, a novel virus, and a bat fly, which is a type of ectoparasite. The study was recently published in Nature Scientific Reports.

“The fact is that they [bats] provide important ecosystem services — insect control, pollination and seed dispersal, to name a few – and we want them around,” said Goldberg in a report to Science Daily. “But bats are also increasingly acknowledged as hosts of medically significant viruses. I have mixed feelings about that.”

Bat flies serve as hosts to viral pathogens, which use parasites to travel from animal-to-animal. The bat fly is eyeless and wingless, and in turn depends on the bat to get around. In this study, a fruit bat was captured, studied, and released by Robert Kityo, PhD, Makerere University in Kampala, Uganda, a co-author of the study.

The bat fly found on this particular bat was infected with a recently discovered rhabdovirus called Kanyawara virus, a relative of the rabies virus. Despite the high content of the virus in the parasite, the virus was not discovered in the bat. The lack of infection does not necessarily mean that the parasite has not reached other species, but on the other hand, it is possible that the virus only affects insects.

It is a fact that ectoparasites have the capability to transmit disease to humans. A well-known example is that ticks transmit Lyme disease. Goldberg acknowledged that bat flies are not an exception; they will bite humans if given the opportunity.

The interest in the topic was spurred from the realization that Ebola pathogens were active in the environment, prior to detection in humans. Therefore, it is possible that simple transfer from an animal to a human ignited an outbreak in West Africa. This discovery opens a new area of research for scientists to explore when trying to prevent future epidemics.

Goldberg, Kityo, and their colleagues are not the only scientists studying virus-carrying bats. Dr. Kevin Olival, PhD, produced work published in Nature that focused on creating a database of viruses that have been known to infect mammals. From the information, Dr. Olival and his colleagues at EcoHealth Alliance determined that bats had the highest proportion of viruses that can be passed to humans.

Using information in the database, researchers have been able to identify areas that have a higher risk of human exposure to undiscovered viruses. The knowledge of the targeted areas, which include Central America, Africa, and Southeast Asia, provide scientists with a map of where to conduct surveillance and be alert for undiscovered diseases infecting humans.