Quarterly Wildlife Mortality Report
Written and compiled by members of the U.S. Geological Survey National Wildlife Health Center - Wildlife Epidemiology & Emerging Diseases Branch.
Avian Cholera Winter 2016-2017 National Summary
The USGS National Wildlife Health Center (NWHC) investigated eight wildlife mortality events between November 1, 2016 and March 1, 2017 in which avian cholera (caused by the bacterium Pasteurella multocida) was either suspected or confirmed as the causative etiologic agent. Five additional event reports were provided by State wildlife management agencies. The 13 events were spread over ten states (California with four events, and one each in Idaho, Illinois, Missouri, Montana, Nebraska, New Mexico, Oregon, Texas, and Washington) and three flyways (Mississippi, Central, and Pacific). The estimated mortality reported to date in these events ranges from less than ten to over 6,500. The three largest events include Canyon County, Idaho (beginning February 2017) with an estimated mortality of 6,500 dabbling ducks as of March 6, 2017; Yolo County, California (January 2017) with an estimated mortality of 3,750 (primarily American coot [Fulica americana] and a small number of dabbling ducks); and McNary National Wildlife Refuge (NWR) and surrounding areas in Washington (February 2017), with an estimated mortality exceeding 2,000. The McNary NWR event primarily involved mallard ducks (Anas platyrhynchos), but also included other dabbling ducks, herons, owls (barn [Tyto alba] and great horned [Bubo virginianus]), and raptors (northern harrier [Circus cyaneus], red-tailed hawk [Buteo jamaicensis], and bald eagle [Haliaeetus leucocephalus]). More information about avian cholera can be found on the NWHC website.
In 2016, the USGS National Wildlife Health Center (NWHC) collaborated with the USGS Amphibian Research and Monitoring Initiative (ARMI) to conduct a spatial risk analysis of the introduction of the invasive salamander fungus Batrachochytrium salamandrivorans (Bsal). Bsal is currently not known to exist in the U.S. and the NWHC-ARMI collaborating scientists were guided by the risk analysis to collect samples from live amphibians with the goal of detecting Bsal if it were present in the highest risk areas. This effort resulted in 7,735 samples collected from over 30 species in 20 states and all samples were negative for Bsal using real-time PCR diagnostics. Additional information about the Bsal surveillance effort is available on the NWHC website.
Avian Influenza 2016-2017 Update
?The U.S. interagency (U.S. Department of Agriculture, Department of the Interior, Centers for Disease Control and Prevention, States, and the National Flyway Council) surveillance program for the detection of highly pathogenic avian influenza (HPAI) virus continued in the 2016-2017 surveillance year. Between July 1, 2016 and February 1, 2017 a total of 33,695 birds was sampled, with 96% of those samples coming from dabbling ducks. Pursuant to this surveillance effort HPAI H5N2 was detected in two mallards (Anas platyrhynchos) including one from Fairbanks-Northstar Borough, AK, in August 2016, and one from Fergus County, MT, in December 2016. In each case, the HPAI virus was the Eurasian-American lineage H5N2 (clade 188.8.131.52) that was first detected in North America in December 2014.
Globally, HPAI H5 subtype detections have continued in wild and domestic birds in Europe, Asia, and Africa during the fall and winter of 2016-2017 with more than 40 countries reporting outbreaks to the World Organisation for Animal Health (OIE). As of March 13, 2017, there have been 576 reported outbreaks in poultry, with nearly seven million poultry destroyed worldwide. Additionally, during the same timeframe there were 638 reported outbreaks involving more than 75 species of free-ranging or captive wild birds (618 of these were H5N8). In January 2017, a mortality event involving more than 1,200 white-winged terns (Chlidonias leucopterus) and other wild bird species was reported in Uganda; HPAI H5N8 was isolated from numerous birds from this outbreak. At least five different HPAI H5 subtypes have been detected during these outbreaks worldwide. For additional information on the current global HPAI situation, please reference the following OIE Situation Report.
National Surveillance Continues to Detect Spread of White-Nose Syndrome in Bats
The USGS National Wildlife Health Center (NWHC) continues to assist State and Federal wildlife agencies nationwide with early detection of Pseudogymnoascus destructans (Pd), and to address specific research priorities identified by partners in conjunction with the White-Nose Syndrome National Plan. During annual bat population surveys, participating State agencies collect bat skin swabs, pooled guano, hibernaculum sediment, and environmental substrate swabs. If white-nose syndrome (WNS) clinical signs are observed in the population, carcasses or wing biopsies are collected for diagnostic testing.
Since 2014, 226 unique hibernacula have been surveyed nationwide. These samples have resulted in the detection of Pd at 81 hibernacula of previously unknown Pd status from 13 states, including 28 sites where there was no physical or behavioral evidence of WNS observed in the bat population. Nearly 95 percent of all detections of Pd originated from samples collected from bats rather than from environmental substrates collected inside of hibernacula. Data analysis and modeling of risk factors associated with Pd movement from data collected during the past three years of the project are currently underway.
In winter 2016-2017, WNS was confirmed for the first time in Nebraska (Cass County) where Pd was first detected in 2015. Alabama reported the first confirmation of WNS in a southeastern myotis (Myotis austroriparius). Finally, Texas announced detection of Pd in six counties (Childress, Collingsworth, Cottle, Hardeman, King, and Scurry) and on two new bat species, cave myotis (M. velifer) and the western sub-species of Townsend's big-eared bat (Corynhinus townsendii townsendii). No clinical signs or mortality were reported in Texas. These findings increase the number of states with confirmed cases of WNS to 30, while the number of affected Canadian provinces remains at five. Three additional states (Texas, Mississippi and Oklahoma) have reported detection of Pd in hibernacula in the absence of confirmed WNS. Northern long-eared bats (M. septentrionalis), little brown bats (M. lucifugus), and tricolored bats (Perimyotis subflavus) remain the species most often positive for Pd.
Despite national surveillance to detect the spread of WNS, the 2016 detection of WNS in Washington State illustrates the ongoing importance of investigating wildlife mortality events 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. We can also answer questions about designing WNS surveillance and response plans relevant to your state and help with testing samples collected as part of opportunistic or targeted surveillance efforts in accordance with the national Pd surveillance strategy. Tribal, State, and Federal agencies with questions about ongoing surveillance efforts, or who may wish to participate, should contact Dr. Anne Ballmann (608-270-2445, firstname.lastname@example.org).
Please visit www.whitenosesyndrome.org for more information about the national multi-agency WNS response effort. A recently completed fact sheet titled “White-Nose Syndrome in North American Bats – USGS updates” is available online. For paper copies, please contact Gail Moede Rogall, email@example.com. Also, a WNS poster and handout are available at https://www.whitenosesyndrome.org/resource/white-nose-syndrome-poster-available-your-use.
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/