Assessment of Zoonotic Disease in Bat Populations of Grand Teton National Park, Wyoming
Authors: Portner Joshua , Gillin Colin 
Published: July 2020

Many man-made structures within Grand Teton National Park (GTNP) provide suitable, if not ideal habitat for bats, especially the Little Brown Myotis (Myotis lucifugus) and the Big Brown Bat (Eptesicus fuscus). In 1995 and 1996, Tom Haraden (GTNP Naturalist) observed many maternity colonies of these species residing within park residences and other buildings. From these observations, this project was developed to expand the knowledge on the local bat populations in GTNP and assess the risk bats might pose to humans within the park buildings they share. Public health concerns are often associated with the status of wild animal populations as potential carriers for a number of diseases. Bats have previously been shown to carry vesicular stomatitis, western equine encephalitis and rabies. Although the ability for bats to carry these and other diseases has been established, there has not been significant research, other than work done with bat Rabies Virus, on the risk that bats and their diseases pose to the human populations. This is despite the presence of bats often living in close proximity to humans. The roofs and attics of manmade structures provide ideal habitat for bat species, especially Myotis lucifugus and Eptesicus fuscus. The ideal daytime bat roost is warm, generally over 90 degrees Fahrenheit, high off the ground to prevent predation, dry, in proximity to a source of water, with adequate sites for clinging or hanging. Nearly every building in Grand Teton National Park fits this description due to the age of the buildings and cracks for bat entrance are common as they require a hole as small as 1/2" to 1" in diameter to gain access. Vesicular Stomatitis, Western Equine Encephalitis, and Rabies Virus are zoonotic diseases that may be carried by bats. If bats of Grand Teton National Park carry these diseases, they would pose a potential risk to the wildlife, domestic animals (including livestock species), and humans living in and around Grand Teton National Park. This risk would potentially extend into the surrounding gateway communities and Yellowstone National Park. The species ranges for Myotis lucifugus and Eptesicus fuscus, the two principle species in this study, cover most of North America, leaving the potential dispersion of a disease over the entire continent and possibly even into South America if transmitted and carried by other bat or bird species. All three viruses cause disease in livestock species including pigs, horses, and cattle, and zoonotic infection in humans. Infections can cause production loss such as severe mastitis in dairy cattle or low weight gain in pigs from vesicular stomatitis, as well as disease in humans ranging from flu-like symptoms to death due to western equine encephalitis infection. Disease from Rabies Virus infection is fatal in all mammalian species, and Vesicular Stomatitis and Western Equine Encephalitis infection does not confer immunity. The aim of this study is to identify the potential risk of bats as carriers of these diseases to provide park managers with baseline information to pursue further disease study and establish structural bat exclusion measures, if needed. As with all park research, the results of this project will also provide information for educational programs.