The United States is home to some 40 different species of bat. Thanks to stories of blood-sucking vampire bats, they've somewhat developed the reputation of a fearsome pest, but in fact they are a vital part of our local environment. Many bats can eat their body weight in insects on a single nightly outing. As such they play a huge role in controlling local populations of real pests: disease-spreading insects.

But across the country something devastating is happening, more than a million bats have now been wiped out due to the rampant spread of a fungal infection known as White Nose Syndrome (WNS).

First discovered in Howe's Cave near Albany, New York in 2006, the mysterious and unusual fungus, which grows on the snouts and wings of many species of bat, was later identified as a member of the Geomyces family that typically lives in cold places. It's not certain whether the presence of the fungus is a symptom or a trigger of bat death. Cases have appeared in Europe where bats appear to be relatively healthy; it's possible the fungus originated in Europe and bats there are immune since they co-evolved with it.

In the US, species affected by WNS appear to wake up and fly around a lot during typical hibernation time, and lose almost all of their body fat reserves, dying of starvation. There is also evidence, however, that the fungus may directly damage wing membranes, making flight more difficult and energy-consuming.

Since 2006 WNS has spread like a raging wildfire across the US, to 115 confirmed hibernation sites in the north-eastern U.S and into Canada, spreading south into Tennessee and as far west as Oklahoma. Between 70 and 90% of infected bats will die. If it continues to spread unchecked it's thought that it will cause the extinction of at least one species of bat, the little brown bat (myotis lucifugus), previously one of the most prolific bat species in the northern United States.

It's not all gloom and doom, however. Many U.S agencies are working to control the problem by keeping people out of caves with hibernating bats and protecting uninfected bat populations. What's more, researchers recently identified some anti-fungal drugs that work well and antiseptics that inhibit its growth. These could be used to treat the bats and 'disinfect' caves and people who go in and out of them to prevent spreading of the fungus. The tricky part will be working out the best way to implement treatments, to determine if they will work on a practical scale.

Comparisons have been made between WNS and other reported wildlife afflictions, such as the fungus causing a worldwide decline in amphibian populations, and the colony collapse disorder affecting Honey Bees. One thing they certainly all have in common is limited publicity, mainly because these aren't diseases that harm humans.  In times of economic hardship, why should we care enough to invest substantial quantities of time and money?  Well, if for no other reason, we must remember that decimating bat populations will likely lead to an increase in disease-carrying insects in our ecosystem, which could then lead to the spread of nasty, headline-grabbing diseases such as West Nile virus (already a problem in some parts of the U.S), Dengue Fever and Malaria.

We need our furry friends!