14 DAY TRIAL // Throughout Latin America, bat colonies are significantly endangered by the rapid spread of the rabies virus, which can decimate entire colonies in no time. As a means of preventing the viral agent from spreading even further, authorities have opted to take drastic measures, including culling entire populations. A new research proves that this approach is ineffective.
In fact, the paper reveals, it could be that killing off entire colonies actually promotes the distribution of the viral agent. The work was carried out by researchers at the University of Michigan (U-M) and the University of Georgia, on bat colonies in Peru, South America.
The main problem with the rabies virus is not that it affects bat populations, but rather livestock and even humans. Bats tend to bite right above the hooves of cows, infecting the animals with the virus, for which there is currently no known cure. Thousands of cattle and other animals fall prey to it every year.
Authorities in Peru have been struggling with this problem since the 1960s, having even attempted to use poison and explosive chemicals to exterminate bat populations. These efforts have largely failed.
The new investigation, published online in the December 2 issue of the esteemed journal Proceedings of the National Academy of Sciences (PNAS), argues that these destructive measures do little to contain the virus. In some cases, computer models have revealed that the creatures are forced into nearby colonies, where they spread rabies even further.
“In the paper last year, we demonstrated that bat colony size wasn't a predictor of rabies prevalence, which indicated that culling hadn't reduced transmission,” says the senior author of the paper, Pejman Rohani. He holds an appointment as an epidemiologist and population ecologist at U-M.
“In the current paper, we do a number of things. First, we fit models that encompass alternative assumptions regarding this system and we identify an important role of movement between colonies,” the investigator goes on to say.
“We then use the best-fitting model to examine what happens under culling, especially if the cull is indiscriminate, rather than targeting infected bats specifically. Again, culling is shown to be ineffective, but now the model helps us understand why that is,” Rohani adds.
Official statistics show that 55,000 people die from rabies infections every year. Around 95 of cases occur in Africa and Asia, primarily due to untreated dog bites.