Few experiences have hit me harder than
walking through a bat graveyard. In March 2014, my colleagues and I were
doing research in a pair of underground mines in northern Illinois.
Five months earlier, these mines had been home to more than 28,000 bats
of five species, but on that day they were tombs, littered with
lifeless, fungus-covered bodies. The bats’ skin was dry and flaking;
their bodies, which hung from the walls near the entrances, were so
emaciated that their bones nearly protruded through their skin.
When we surveyed the area, we found just 1,023 live bats in one mine
and 5,237 in the other. More than 75 percent of the bats were dead from
white-nose syndrome, an emerging disease caused by the fungal pathogen Pseudogymnoascus destructans.
We left Illinois the next day emotionally spent. Our team, along with
the broader community of biologists who study this disease, has been
searching for ways to prevent this pattern of devastation from repeating
itself. Sadly, white-nose syndrome continues to ravage bat populations
as it spreads westward across the continent. (See map here.) Over the
past seven years, the disease has killed millions of bats in 25 states
and five Canadian provinces, making it one of the most devastating
diseases to affect mammals in recorded history.
Unfortunately, bats are not the only animals struggling to survive in
the face of emerging pathogens. Amphibians have been decimated by
chytridiomycosis, another fungal disease that is now found on all
continents except Antarctica and is believed to have driven more than
100 species to extinction. Meanwhile, millions of birds in North America
have died from West Nile virus, which became the most widespread
mosquito-borne disease on the planet when it spread across the Americas
in the past decade.
Such destructive outbreaks are often spurred by the emergence of
pathogens in new locations, where hosts have not yet evolved sufficient
defenses against these diseases. Understanding what shapes these
epidemics is instrumental in bringing them under control and reducing
their impacts on the world’s biodiversity.
