White-Nose Syndrome Spreading Rapidly

WNS fungus on the nose of a little brown bat

photo courtesy of Ryan von Linden, NY Dept of Environmental Conservation

Since my first post on White-Nose Syndrome, three more species and several more US states have been affected. First detected in February 2006 in New York state, the then-unidentified disease spread to Vermont, Massachusetts, and Connecticut by Spring 2008. In Spring 2009, it spread to New Hampshire, New Jersey, and Pennsylvania and then south into Virginia and West Virginia. (There was even one case confirmed in France in December 2009 - a bat tested positive for the WNS fungus but showed no symptoms.) In February/March 2010, it spread out into Tennessee, Maryland, and Ontario, and in April/May 2010, the fungus was confirmed on bats in Delaware, Missouri, Oklahoma, and Québec. This brings the total to 14 US states and 2 Canadian provinces.

The rate that it is spreading is quite alarming - it was thought that once it hit the more southern latitudes or more northern latitudes, it would slow down. Unfortunately that has not been the case, and with such high - sometimes 100% - mortality rates at many of the caves, coupled with bats' relatively slow reproduction rates, it is quite possible and sad that some of these affected species - some of which are already endangered - may become extinct.

There's a heartbreaking article in BCI's Summer 2010 issue, which talks about the emotional toll WNS has had on bat scientists, managers and conservationists. These individuals have given their lives to working with and protecting these bats year after year, and they've come to regard these little guys as friends, so seeing cave floors and entrances littered with bat carcasses is absolutely devastating. Some of these bats have occupied these caves for 10,000 years (like those in Aeolus Cave in Vermont). And now they're gone.

Researchers now having a better understanding of how bats are killed by the fungus, how they react to the fungus, and how their immune systems respond, but they don't yet know how to stop the spread. Some researchers say that developing a vaccine is the best hope - though vaccinating colonies of bats would pose an extremely difficult task. Or perhaps bats may just naturally develop a resistance, and these individuals can then slowly but surely repopulate themselves.

The three newly-affected species are the endangered gray myotis (Myotis grisescens) in Missouri, the southeastern myotis (Myotis austroriparius) in Virginia, and the cave myotis (Myotis velifer) in Oklahoma. Fortunately, while testing positive for the fungus, these three species have not exhibited any symptoms of the disease, like being emaciated or prematurely emerging from hibernation. Also, the fungus was only on the skin, not in the tissue underneath. However, it's not yet understood if the fungus precedes the symptoms by a season or two or if the disease is just behaving differently in these different climates.

Unfortunately, these newly-affected species open the door to the WNS fungus spreading into the western United States and Mexico because the cave myotis often share caves with migratory Mexican Free-Tails (Tadarida brasiliensis) - bats so commonly found in western and southern states, especially Texas.

The southeastern myotis also has a pretty wide u-shaped range, from parts of Indiana and Illinois down to the Mississippi Delta, into East Texas and then along the Gulf and Atlantic coasts up to North Carolina. This species not only roost in caves but also in hollow trees, bridges, buildings, and underground cisterns. (So far WNS has only affected bats in hibernation caves and mines.) Again, it's hoped that the warmer climates - where bats don't hibernate as deeply - will possible stop or at least slow the disease, but sadly, there's just no predicting what might happen.

For the latest WNS news, see BCI's WNS page.