Category: General Article
White nose syndrome (WNS) is the only one fungal disease known to kill millions of mammals in a large geographic area. The name refers to the main symptom of the disease, a white fuzz on bat faces and wings. The cause of WNS is a fungi, Pseudogymnoascus destructans (Pd). Pd is spread through contact between animals and airborne dispersal.
Like fungi that have devastated elm and chestnut trees, Pd is not native to North America. Similar to human AIDS patients, hibernating bats have weakened immune systems, as well as low body temperatures, both of which allows cold-adapted fungi like Pd to successfully attack bats. Irritation from the resulting skin damage awakens bats so often during hibernation that they exhaust their energy reserves and become too weak to fly and feed. Even if they survive starvation, they may be killed by an overreaction of their own auto-immune systems which become reactivated after hibernation.
Because bats are highly social and live in colonies, Pd can quickly decimate a population once it is introduced, decreasing bat populations by up to 90%. Pd does not affect people but it can completely destroy a large colony while the bats hibernate for the winter.
As of early 2017, the U.S. Fish and Wildlife Service estimates that between 5.7 million and 6.7 million bats have died from the fungus since 2012.
WNS was first identified in the eastern United States and within several years spread to the Midwest. It is also known from many countries in Europe as well as Siberia and China, places where bats have developed immune resistance to Pd. The first case of it in the western United States was discovered in Washington in May 2016. So far, there has only been three cases of the fungus in this state. As of March 2017, there have been no reported cases of Pd in Oregon.
All animals have an important role to play in an ecosystem, but bats are especially valuable to people. Bats are fundamental for the control of many of the world’s insect populations, especially insects that fly at night. In some cases — as with mosquitoes — bats are controlling an insect with the potential to spread deadly diseases to human beings or their pets and livestock. They also limit insects that could attack and destroy food crops. Furthermore, a number of bat species are valuable pollinators, fulfilling the same role as bees in many parts of the world. In the United States, pollinator bats are particularly abundant in the desert southwest.
Understanding how some bats can live over forty years, far longer than most any other small mammal, has important implications for human longevity. If we can learn how to slow such an unprecedented epidemic, we may be able to reduce human mortality from fungal diseases, the rates of which have increased thousands of times in the last half century.
• As with all wildlife, leave bats alone. Do not handle any bat and report any motionless or dead bats to wildlife officials.
• Limit the spread of WNS by limiting your contact with bats. This means avoid entering areas where bats may be living, such as rock cliffs, talus areas, lave tubes, caves or mines. If you do go into these areas, make sure you are not bringing in apparel or equipment that have been in contaminated areas like Washington and states east of the Rocky Mountains. The fungal spores are too small to see, so the best thing to do is to wear different clothes and shoes when visiting another cave. Thoroughly wash your clothes and shoes after visiting any bat habitat. Decontamination guidelines can be found by clicking here.
• Improve or create bat habitats. You can create a bat-friendly environment by minimizing the clearing of native plant life, and protecting streams and wetlands where insects breed (the bat’s major food source). You can find additional tips by clicking here.