Hibernating bats and HIV-AIDS patients face a similar risk.
A hyperactive
immune system may cause dangerous tissue damage in both humans dealing with
HIV-AIDS and bats suffering from white-nose syndrome (WNS). The immune system
over-reaction, known as immune reconstitution inflammatory syndrome (IRIS),
occurs when the immune system becomes active after being dormant.
"We see strong similarities between human IRIS and the pathology
associated with WNS , with potentially fatal outcome in bats," said Carol
Meteyer of the U.S. Geological Survey and lead author of a study on IRIS
published in the journal Virulence, in a press release.
"We hope that these findings will
stimulate more experimental studies that yield insight into the role of the
immune response during IRIS in humans as well as hibernating bats."
In HIV-AIDS patients, IRIS can occur after treatment with antiretroviral
drugs allow their immune systems to recover. HIV-AIDS patients sometimes develop
infections while their immune system was weakened. Once the drug treatments
allow the white blood cells of the immune system to recover, the cells can go
into overdrive attacking the infection. The inflammation that follows can cause
damage to healthy tissue.
In bats, IRIS may happen after the bats wake up from hibernation. To conserve
energy, most of the bats biological functions, including the immune system, go
dormant during hibernation. White-nose syndrome attacks the bats while their
immune systems can't fight back. The fungus Geomyces destructans takes advantage of this
and begins devouring the bats alive, coving them with a white fuzz that gives
white-nose syndrome its name.
The fungal
infection alone can be enough to kill the bats. However, if they survive the
winter, when their immune system comes back from its hibernation dormancy it
can over-react to the white nose infection. The inflammation can damage tissues,
just as in HIV-AIDS patients, and can prove especially deadly if it affects the
wings.
IMAGES: Greater mouse-eared bat, Myotis myotis, with white fungal growth around its muzzle, ears, and wing membranes (Tamás Görföl, Centers for Disease Control and Prevention, Wikimedia Commons)
