National Wildlife Health Center

...advancing wildlife and ecosystem health

Quarterly Wildlife Mortality Report
October 2016

Written and compiled by members of the U.S. Geological Survey National Wildlife Health Center - Wildlife Epidemiology & Emerging Diseases Branch.

Detection of EA/AM H5N2 HPAI in a Mallard from Alaska

On August 26, 2016, the Animal and Plant Health Inspection Service (APHIS) of the U.S. Department of Agriculture (USDA) confirmed the detection of Highly Pathogenic Avian Influenza (HPAI) H5N2 in a mallard duck (Anas platyrhynchos) from Alaska. Samples were collected as part of the national surveillance for HPAI in wild birds by the Alaska Department of Fish and Game during live bird banding at a waterfowl refuge in Fairbanks, North Star Borough, Alaska. Genome sequencing analysis shows that the Alaska isolate is a strain of Eurasian/American (EA/AM) H5N2 HPAI with over 99 percent similarity to the virus isolated from a northern pintail duck (Anas acuta) in Washington State in December 2014. Enhanced sampling of wild birds in proximity to this detection in Alaska is ongoing to determine if additional HPAI viruses can be detected in this region. Avian influenza virus has not been identified in domestic birds in Alaska as of late September.

Since the detection of HPAI viruses in wild birds and poultry in the United States and Canada in December 2014, the USGS National Wildlife Health Center (NWHC) has continued to work closely with the USDA APHIS Wildlife Services, the U.S. Fish and Wildlife Service, and state wildlife agencies to implement enhanced mortality investigations and national surveillance in wild birds for HPAI viruses. This is the first detection of HPAI in a wild bird since November 2015 when it was detected in a hunter-harvested mallard in Oregon (although that case remains unconfirmed as full characterization by virus isolation and genetic sequencing was unsuccessful because no virus was isolated from this bird).

For an up-to-date summary of positive results from combined federal and state agency HPAI national surveillance in wild birds for the 2016-2017 surveillance year, please view this table: Wild Bird HPAI Cases in the U.S.

This summary was excerpted from a NWHC Wildlife Health Bulletin available at this link.

Virulent Newcastle Disease Virus in Double-Crested Cormorants

In July and August, 2016, the USGS National Wildlife Health Center (NWHC) received multiple reports of sick or dead juvenile double-crested cormorants (Phalacrocorax auritus) from several states in the Great Lakes region. Common clinical signs observed included increased fledgling mortality at rookeries, neck weakness, unilateral wing paralysis, incoordination, and tremors. In some locations, concurrent mortality in other species including gulls and pelicans was reported.

Subsequent to the investigation, virulent Newcastle Disease virus (vNDV) was confirmed by genetic sequencing in 12 cormorants submitted from four counties in Minnesota (Big Stone, Mille Lacs, Pope, Rice) and two counties in Wisconsin (Dodge, Door). Cormorants from Lake County, Indiana screened positive for avian paramyxovirus-1 (APMV-1) by matrix PCR, but vNDV was not isolated. It is possible that vNDV was present, but that there was insufficient viable virus for a positive isolation. Gulls and pelicans collected with cormorants in Big Stone County, Minnesota tested positive for salmonellosis and were negative for vNDV. The NWHC’s experience with previous vNDV outbreaks has shown that sympatric species are rarely affected by vNDV. All birds submitted from these outbreaks screened negative for Highly Pathogenic Avian Influenza virus.

Certain strains of APMV-1 can cause significant wild bird mortality, but these events are typically limited to juvenile double-crested cormorants. Some strains of APMV-1 classified as vNDV, including some strains isolated from cormorants, can also cause significant disease in poultry and are reportable to state and federal agricultural officials. Avian paramyxovirus-1 can cause mild self-limiting conjunctivitis in humans, therefore the use of eye protection or face shields should be considered when investigating these events. As a routine precaution when handling any sick or dead birds, personal protective equipment including gloves, rubber boots, and disposable or cloth coveralls should be worn and hands should be thoroughly washed afterwards.

For additional information, see this Wildlife Health Bulletin.

Batrachochytrium salamandrivorans (Bsal) Surveillance Update

A newly identified fungal pathogen, from Asia, Batrachochytrium salamandrivorans (Bsal), has caused mass mortality events and severe population declines in European salamanders via introduction into wild populations from the pet trade. North America has the highest diversity of salamanders in the world and introduction of this pathogen could be devastating, not only to local populations but also to global salamander biodiversity. The USGS National Wildlife Health Center (NWHC) is working collaboratively with the USGS Amphibian Research and Monitoring Initiative (ARMI) to determine whether Bsal is present in North American salamander populations in targeted locations with high biodiversity and increased risk of exposure to the Bsal pathogen (Yap et al., 2015; Richgels et al., 2016). The NWHC and ARMI are working to reach a 10,000 sample goal in these high-risk locations. Samples are being collected by live capture and swabbing of salamander and newt species. As of August 2016, there have been no detections of Bsal in the 4,521 salamander and newt samples tested from 20 species submitted from 19 states. Sampling and diagnostic testing is ongoing and, once completed, the results will be incorporated with previous risk assessments (Yap et al., 2015; Richgels et al., 2016) to produce updated risk estimates of Bsal in the U.S.

For information on Bsal diagnostic and epidemiological activities at the NWHC, contact Dan Grear, NWHC Bsal Coordinator, dgrear@usgs.gov or C. LeAnn White, NWHC Wildlife Epidemiology and Emerging Diseases Branch Chief, clwhite@usgs.gov. For more information about Bsal field sampling and amphibian research activities, contact Hardin Waddle, USGS ARMI Bsal Coordinator, waddleh@usgs.gov.

References:

  • Richgels KLD, Russell RE, Adams MJ, White CL, Grant EHC. 2016. Spatial variation in risk and consequence of Batrachochytrium salamandrivorans introduction in the USA. R. Soc. Open Sci. 3: 150616. http://dx.doi.org/10.1098/rsos.150616
  • Yap TA, Koo MS, Ambrose RF, Wake DB, Vredenburg VT. 2015. Averting a North American biodiversity crisis: A newly described pathogen poses a major threat to salamanders via trade. Science 349(6247): 481-482. http://escholarship.org/uc/item/3bn651f5

Corallimorph Infestation at Palmyra Atoll National Wildlife Refuge

Palmyra Atoll National Wildlife Refuge (NWR) is jointly managed by the U.S. Fish and Wildlife Service (FWS) and The Nature Conservancy. Palmyra was heavily altered by the U.S. Navy during World War II with construction of multiple causeways and airstrips built from dredged corals. Today, the atoll has partly recovered and is known for its diverse coral reefs and associated biota and, on land, large stands of Pisonia forests and numerous species of land crabs and nesting seabirds. In 1991, a longline fishing vessel ran aground on the western shelf of Palmyra and, in 2007, the USGS National Wildlife Health Center’s (NWHC) Honolulu Field Station (HFS) documented invasive corallimorphs (CM) overgrowing coral reefs surrounding the wreck (Work et al., 2008). A follow-up survey in 2011 revealed the infestation was spreading, thus prompting the FWS to remove the wreck in 2013. In 2016, the HFS conducted a follow-up survey of CM infestation in collaboration with Dr. Benjamin Neal of Bigelow Laboratories.

Compared to 2007 and 2011, it appears that in 2016 the CM infestation at the site of the shipwreck has abated considerably. However, heavy infestation on the shelf persists, both northwest and southeast of the wreck site. A new heavy infestation is also present at Penguin Spit to the southwest of the atoll. There, the reefs and associated sessile biota such as giant clams are smothered with CM infestation extending to a depth of 18 m.

Iron or other material leaching from metal may be associated with the spread of CM from the longline wreck; thus, removal of the wreck may explain the observed reduction of CM at the wreck site. In 2007, HFS noted a decreasing gradient of CM with increasing distance from mooring buoys at Penguin Spit. Replacing mooring buoy chains with non-metallic materials (e.g., Kevlar) would provide an additional test of the hypothesized metal-CM association.

To protect the long-term integrity of the atoll, it may be necessary to identify and implement CM eradication techniques. A proof-of-concept was implemented by HFS in collaboration with Dr. Greta Aeby (University of Hawaii) in 2011 using tarps, sandbags, and chlorine to successfully eradicate CM from 40 square feet of benthos, with the eradication continuing over a year. Upscaling this technique offers one possibility for long-term CM management efforts at Palmyra.

References:

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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