New clues about a mysterious bat-killing disease
New research findings have pinpointed the cause of a deadly disease in bats, but mysteries remain about why animals in the US are more vulnerable to it than their European counterparts. The disease, called White-Nose Syndrome, was first spotted in a cave in New York State in 2006, explains UCD’s Dr Sébastien Puechmaille, a post-doctoral researcher at the UCD School of Biological and Environmental Sciences. “Hundreds, or even thousands of bats were dying when they were hibernating,” says Dr Puechmaille. “The floor of the cave was full of dead bats, which is very unusual. People had no clue what was happening.” Since then, around five million bats are thought to have died from the syndrome as it has spread westward into the continent, he adds.
The one tell-tale mark of this mysterious happening was that the dead bats had white noses (hence the name of the syndrome) from a fungus that was growing there. In 2009, the fungus was described as a newly discovered species, Geomyces destructans, and researchers suggested that the fatal syndrome may have been waking bats more frequently than usual during hibernation, meaning they were running down their energy reserves to a point where they could not survive.
Meanwhile, Dr Puechmaille and colleagues went looking in Europe and found evidence of the fungus in bat habitats in several countries. “I started looking in Europe and I first discovered it in France in 2009,” he recalls. “Then I worked with colleagues in Germany and we found it in around 15 countries throughout Europe. It is widespread.” But crucially, the fungus didn’t seem to cause a problem for bats in Europe. “We didn’t find massive mortality related to this fungus,” says Dr Puechmaille.
Last year, Dr Puechmaille and Dr Emma Teeling from UCD led the White-Nose Syndrome Consortium, a team of more than 60 scientists from 30 countries, to look at what had been discovered. A resulting paper, published in Trends in Ecology and Evolution, reviewed the situation and also mapped out future research that would help to improve our understanding of the condition.
The new study in the Proceedings of the National Academy of Sciences, by researchers in Canada, the US and Germany, has carried out some experiments that were called for by the expert group: they inoculated bats from the US with Geomyces destructans fungus that had come from Europe. And the result? The bats woke more frequently during hibernation, with fatal consequences.
The study shows that the fungus is the causative agent of the syndrome, and it lends weight to the theory about running down energy reserves in the animals, according to Dr Puechmaille. “The experiments show the European and US isolates have the same pathology in North American bats,” he says. “So it looks like the American isolate is not more virulent than the European isolate.”
Although Dr Puechmaille was not directly involved in that piece of the research, he welcomes the findings.
“It is a big step,” he says. “Now we can completely concentrate on working on Geomyces, we know we are going in the right direction.”
As for why the European bats seem to shrug off the effects of the fungus while bats in the US succumb, much remains to be found out. “It may be that bats in Europe have acquired immunity to this fungus,” says Dr Puechmaille. “Or it may be something to do with the environments of the caves. We don’t know.”
He is continuing the work, surveying European sites and further afield to collect samples of the fungus, carry out genetic analysis and investigate the pathology associated with the fungus growth on bat wings. “There is plenty still to find out,” he says.
In parallel, Dr Emma Teeling is looking at the molecular causes of this potential immunity.
Article written by Dr Claire O’Connell