Quarterly Wildlife Mortality Report
January 2016 to March 2016
Written and compiled by members of the U.S. Geological Survey National Wildlife Health Center - Wildlife Epidemiology & Emerging Diseases Branch.
White-nose syndrome confirmed in bat from Washington State
White-nose syndrome (WNS), a devastating disease of hibernating bats, has now been confirmed in the northwestern United States. A single, western subspecies of little brown bat (Myotis lucifugus) from King County, Washington was found unable to fly by a hiker in mid-March and taken to Progressive Animal Welfare Society (PAWS), a local wildlife rehabilitation center and animal shelter. The bat had evidence of wing membrane damage and died within several days of admittance to PAWS. The carcass was then submitted, in consultation with the Washington Department of Fish and Wildlife (WDFW), to the USGS National Wildlife Health Center (NWHC) for examination. At NWHC, the bat was confirmed to be infected with Pseudogymnoascus destructans (Pd), the fungus that causes WNS. The bat additionally had histopathological lesions consistent with WNS. The species identity of the bat was confirmed by genetic analysis. This discovery was made public on March 31, 2016, in a joint news release by the WDFW, the U.S. Fish and Wildlife Service, and the USGS. The area where this bat was found is approximately 1,300 miles from the previous westernmost detection of Pd. This new detection represents a significant change in the geographic distribution of WNS and to the previously established pattern of fungal spread in North America. White-nose syndrome has now been confirmed in 29 states (Rhode Island also had its first confirmed case of WNS in 2016) and five Canadian provinces (WNS map). The fungus has been detected on bats lacking clinical signs of WNS in another three states (Mississippi, Nebraska, and Oklahoma). As this latest detection represents a large geographic expansion in the distribution of Pd within North America, genetic analyses are underway to determine the origin of the fungal pathogen isolated from the Washington bat.
The NWHC is currently working with WDFW, Idaho Department of Fish and Wildlife, Oregon Department of Fish and Wildlife, and other federal agencies to assist with additional active surveillance in the Pacific Northwest to determine prevalence and geographic range of Pd. Enhanced surveillance efforts are also underway in British Columbia, Canada in accordance with the Canadian National WNS Plan. The recent detection of WNS in Washington additionally illustrates the importance of wildlife mortality investigation as part of a comprehensive wildlife disease surveillance strategy, and we encourage wildlife managers to report unusual bat mortality or bats displaying clinical signs suggestive of WNS to the NWHC for further investigation.
Chronic wasting disease update
Chronic wasting disease (CWD) is a fatal, contagious, neurodegenerative disease of cervids (Family Cervidae), including North American deer (Odocoileus sp.), elk (Cervus canadensis) and moose (Alces alces). The disease continues to be detected in new geographic locations and with increasing prevalence in some areas where the disease has been monitored the longest. Since the beginning of calendar year 2016, CWD has been documented in free-ranging deer and elk populations in new geographic locations within in Alberta, Nebraska, Texas and Wyoming, and was detected for the first time in Arkansas. The disease was also detected in captive white-tailed deer (O. virginianus) facilities in Texas and Wisconsin. A map of the current known distribution of CWD in North America is available from the USGS National Wildlife Health Center (NWHC). In addition, the first detection of CWD in wild reindeer (Rangifer tarandus), and the first documented CWD cases in Europe were announced by the Norwegian Veterinary Institute and the Norwegian Environment Agency.
The first detection of CWD in Arkansas, announced by the Arkansas Game & Fish Commission (AGFC) in February 2016, was a hunter-killed cow elk taken in 2015 in Newton County. Subsequent to this initial detection AGFC has conducted outbreak surveillance to determine the geographic distribution of CWD and the disease prevalence within the affected area. To date, CWD has been detected in five contiguous northwestern Arkansas counties in both white-tailed deer and elk, and 23% (62 of 266) of the randomly collected deer samples have been positive. This high level of prevalence, as measured in the initial round of sampling, suggests that CWD has been present and undetected in this population for a protracted period of time. In a second phase of sampling designed to determine geographic distribution, AGFC is collecting samples from vehicle-killed deer, deer found dead, and animals exhibiting clinical signs consistent with CWD.
On April 4 2016 the Norwegian Veterinary Institute announced detection of CWD in a cow reindeer from the Nordfjella population in southern Norway. Researchers with the Norwegian Institute for Nature Research (NINA) were capturing reindeer for a telemetry project in March 2016 when they observed the animal. The adult female, sick and in less than average physical condition, died and was submitted for necropsy. Brain samples collected from the reindeer tested positive for CWD by enzyme-linked immunosorbent assay (ELISA), western blotting, and immunohistochemistry (IHC). Caribou (Rangifer tarandus) were previously determined to be susceptible to CWD in a research setting and scientists expressed concern over how the disease would manifest in a highly-gregarious cervid species. The detection, from the area of Sogn and Fjordane, is the first report of CWD in free-ranging reindeer and the first report in Europe. Norway routinely samples reindeer as a part of their national surveillance program for CWD and other transmissible spongiform encephalopathies (TSEs).
Subsequent to intensified disease monitoring, the Norway Environment Agency announced, on May 25, 2016, the detection of a CWD-positive moose (Alces alces, commonly referred to as elk in Europe) from the Selbu municipality of Sor-Trondelag. This region is approximately 300 kilometers from where the initial CWD-positive reindeer was detected. On June 15, 2016, the Norwegian Veterinary Institute announced a second CWD-positive moose, also from the Selbu region. Both moose were necropsied at the Norwegian Veterinary Institute in Trondheim and their brain tissue tested positive for CWD by ELISA and western blot. Both moose were adult pregnant females. The first moose was euthanized based on clinical signs consistent with CWD. The second, found dead in a river, was in normal condition and necropsy revealed trauma as the cause of death. At this point, the origin of CWD in Norway and any relationship between the reindeer and elk cases is undetermined.
To view, search, and download historic and ongoing wildlife morbidity and mortality event records nationwide visit the Wildlife Health Information Sharing Partnership event reporting system (WHISPers) online database: http://www.nwhc.usgs.gov/whispers/
To request diagnostic services or report wildlife mortality: http://www.nwhc.usgs.gov/services/