National Wildlife Health Center

...advancing wildlife and ecosystem health

 

Quarterly Wildlife Mortality Report

April 2015 to June 2015

Written and compiled by the U.S. Geological Survey National Wildlife Health Center Epidemiology Team members: Anne Ballmann, Barb Bodenstein, Bob Dusek, Dan Grear, and Jenny Chipault


 

Highly pathogenic avian influenza in North America – 2015 second quarter update

As of early September 2015, the most recent detection of highly pathogenic avian influenza (HPAI) viruses in wild North American birds was a mallard from Davis County, Utah sampled in late-July 2015. This mallard, and the June detections of HPAI in Canada geese (Branta canadensis) in Michigan (reported by the Michigan Department of Natural Resources) and a black-capped chickadee (Poecile atricapillus) in Minnesota (reported by the Minnesota Department of Natural Resources), demonstrate that HPAI was present in resident wild birds during the summer.

The USGS National Wildlife Health Center (NWHC) is a member of the Interagency Steering Committee for Surveillance for Highly Pathogenic Avian Influenza in Wild Birds and, in this role, is testing samples from live birds and hunter-harvested birds that are collected by participating agency partners in the Mississippi and Atlantic Flyways.

The NWHC also continues to monitor for HPAI viruses by testing dead birds submitted for diagnostic evaluation (nationwide) and is the leading partner in mortality and morbidity investigation and associated diagnostics within the Interagency Strategic Plan. Mortality investigations will facilitate early detection of HPAI in wild birds and will increase our knowledge of the spatial extent and species involved. Wildlife managers should remain vigilant for wild bird morbidity and mortality events and continue to contact NWHC to discuss submission and testing of carcasses from events that meet the expanded submission criteria. Wildlife management agencies that investigate morbidity and mortality events independently or in collaboration with other diagnostic laboratories are strongly encouraged to report these events to the NWHC using our reporting worksheet so that information can be captured on a national scale and displayed on WHISPers, a wildlife health information sharing website, to increase situational awareness.

In addition, the NWHC is conducting research into the ecology of HPAI and other avian influenza viruses in the Mississippi Flyway. This research began in the summer of 2015 and involves sampling wild waterfowl and peridomestic avian and mammalian species to test for active infection with avian influenza viruses and serological exposure to the HPAI viruses that were previously detected in 2015. This collaborative effort includes partnerships with the U.S. Fish and Wildlife Service, Wildlife Services within the U.S. Department of Agriculture Animal and Plant Health Inspection Service, the Iowa Department of Natural Resources, the Minnesota Department of Natural Resources, the University of Minnesota, the Wisconsin Department of Agriculture Trade and Consumer Protection, the Wisconsin Department of Natural Resources, and private landowners.

To date, no humans or other mammals have shown signs of disease from these particular viruses but field personnel handling live or dead wild birds should take appropriate precautions. For more information, see the USGS Role and Response to Highly Pathogenic Avian Influenza fact sheet.

Small mammal mortality in Idaho

Mortality among small rodents, including southern red-backed voles (Myodes [formerly Clethrionomys] gapperi), montane voles (Microtus montanus), gophers (Thomomys sp.), red squirrels (Tamiasciurus hudsonicus), bushy-tailed woodrats (Neotoma cinerea), and unspecified mice, was reported in southwestern Idaho beginning in early June 2015. Carcasses were found on lawns and in parking lots individually or in clusters of five to 20 animals. Total dead was estimated at 2,000 individuals as of early July. In May 2015, plague mortality resulting from an infection with the bacterium Yersinia pestis had been confirmed by Idaho Bureau of Laboratories and Idaho Fish and Game in Piute ground squirrels (Urocitellus mollis) around Boise. The NWHC examined carcasses of 10 montane voles, two meadow voles (Microtus pennsylvanicus), and one red squirrel. No definitive evidence of a causative agent was identified. Grossly, the majority of voles were emaciated and had evidence of impact trauma. Enlarged submandibular lymph nodes were detected in two voles. Bacterial cultures and/or polymerase chain reaction (PCR) tests of lungs, livers, and spleens from multiple voles tested negative for Francisella, Pasteurella, Salmonella, and Yersinia spp..

There have been numerous cases of plague and tularemia in wildlife, domestic pets, and humans (some fatal) reported in western states this spring and summer. Plague reports began in April in Arizona, and have continued through August, involving seven additional states (California, Colorado, Idaho, Nebraska, New Mexico, Utah, and Wyoming). Tularemia, caused by the bacterium Francisella tularensis, was first reported in May among rabbits and rodents and cases have continued through August involving eight states (Arizona, Colorado, Montana, Nebraska, New Mexico, North Dakota, South Dakota, and Wyoming). Transmission of these agents can occur through consumption of contaminated food or water, inhalation, contact with infected individuals (including pets) and carcasses, or through the bite of infected insect vectors such as fleas or ticks. Therefore, proper handling and cooking of game meat, safe water sources, and insect repellant are advised to reduce exposure. For more information, visit the Centers for Disease Control and Prevention website or the NWHC tularemia or plague circulars.

Seabird mortality along southern coastal Alaska

Since May 2015, the USGS National Wildlife Health Center (NWHC) has been assisting the U.S. Fish and Wildlife Service (USFWS) Region 7 Migratory Bird Management Office, several USFWS refuges, the National Park Service, and the Alaska Department of Fish and Game with investigations of multiple seabird mortality events along the Bering Sea and Pacific Ocean coastal areas of the Aleutian Islands East, Kodiak Island, Kenai Peninsula, and Prince William Sound. Estimates of the size and scope of these events have ranged from a few birds affected (~5-10) to >100 birds being found sick or dead at one time and location. The primary avian species reported to be affected to date include murres (common [Uria aalge] and thick-billed [U. lomvia]), sooty shearwaters (Puffinus griseus), black-legged kittiwakes (Rissa tridactyla), horned puffins (Fratercula corniculata), and glaucous-winged gulls (Larus glaucescens). Some of these avian mortalities have been concurrent with significant whale, pinniped, sea otter (Enhydra lutris), and fish mortalities throughout the summer.

Diagnostic investigations have been challenging due to remote locations and/or lack of suitable carcasses. As of August 2015, the NWHC has received multiple avian carcasses from field partners. The primary finding for both juvenile and adult bird specimens received has been emaciation; a few individuals have also had mild to moderate intestinal parasite infections. All birds examined have tested negative for highly pathogenic avian influenza viruses and pathogenic bacteria such as Pasteurella multocida. The cause(s) of the emaciation are still being pursued and diagnostic tests are still in progress, including algal toxin analysis. An extensive Pseudo-nitzschia bloom (the algae that causes domoic acid poisoning) in Kachemak Bay and other areas has been reported for much of this summer, but it is unknown at this time if it is responsible for these mortality events. Water temperatures have been higher than normal off the coast of Alaska during the spring/summer 2015, likely due to “the blob” (unusual and persistent masses of warm water) and/or El Nino activity in the Pacific Ocean.

The NWHC is partnering with the USFWS, the National Oceanic and Atmospheric Administration (NOAA) Marine Mammal Stranding Network, the Aleutian Pribilof Islands Association, the USGS Alaska Science Center, and others to gather more information regarding ecosystem parameters concurrent to these mortalities such as oceanographic conditions, shellfish closures due to paralytic shellfish poisoning, forage fish availability, and marine bird populations. According to the NWHC historic records, significant mortalities involving these avian species have previously been reported from these areas of Alaska during 1983, 1989, and 1998, but time frames were March-May and September-October. Diagnostic findings on birds examined during previous events were emaciation with unknown underlying causes.

The NWHC encourages wildlife biologists and resource managers along the west coast of the lower 48 states to be aware that mortalities might become more widespread during migration and as environmental conditions change in autumn; please report marine bird and mammal mortality event observations to help determine the overall magnitude and scope of these events and potential impacts to species involved. For further information, please contact the NWHC epidemiology team via email: nwhc-epi@usgs.gov or phone: (608) 270-2480.

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/

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