(e) = estimate

Southeastern Cooperative Wildlife Disease Study (SCW), USGS National Wildlife Health Center (NW), California Fish and Game (CFG), Florida Game and Fish (FL).

Written and compiled by Kathryn Converse/Rex Sohn - Western US, Grace McLaughlin - Eastern US, Christine Lemanski , NWHC. The Quarterly Wildlife Mortality Report is available at http://www.nwhc.usgs.gov. To report mortality or receive information about this report, contact the above NWHC staff, or for Hawaiian Islands contact Thierry Work. Phone: (608) 270-2400, FAX: (608) 270-2415 or e-mail: kathy_converse@usgs.gov. USGS National Wildlife Health Center, 6006 Schroeder Road, Madison, WI 53711.

Quarterly Mortality Reports

West Nile Virus Continued Spread across North American Continent in 2003 (CORRECTION).
By the end of 2003, West Nile virus (WNV) activity was detected in 45 continental states and the District of Columbia, 7 Canadian provinces, and in several Mexican states. Interestingly, although WNV was detected in the state of Washington in 2002, WNV activity was not detected there in 2003. As of January 2004, over 13,000 dead birds have tested positive for WNV. The list of species found positive for WNV continues to grow longer, currently with over 220 avian, 22 mammalian and 1 reptilian species. In addition to the wildlife species, almost 6000 horses and over 11,000 human cases (including 231 deaths) in 2003 were reported by public health agencies in the United States and Canada. Although the number of reported human cases was significantly greater in 2003, the actual number of the severe form of disease (meningitis/encephalitis) is similar to that reported in 2002. At this time, there is no direct evidence for any significant change in the virulence of the WNV strain in North America. The Midwestern states were the primary foci of activity in 2002, while in 2003 the Rocky Mountain states of CO, WY, and MT were the major foci of virus activity in 2003. Based on observed trends of WNV activity in North America, public health and wildlife officials in the western United States are anticipating high WNV activity in their states in 2004. It remains unknown if and when WNV will arrive in Hawaii and Alaska, and the impact WNV will have on the avifauna of these states.

Acanthocephalan infections in Massachusetts common eiders.
Beginning in early May 2004 and continuing into early June, sick and dead common eiders were reported along Cape Cod, Massachusetts. Approximately 350 common eiders were reported dead in Wellfleet Bay through counts made by wildlife rehabilitators and National Park Service personnel. Birds were submitted to the National Wildlife Health Center, where it was found that large numbers of acanthocephalans had severely damaged the intestines. Some birds also had very high numbers of cestodes that may have compromised the birds’ nutritional status. The NWHC Epizoo database contains information on 14 mortality events involving common eiders. There were eight mortality events that occurred before 1990; six were attributed to avian cholera and occurred off the coast of Maine. Of the six mortality events since 1990, one on the St. Lawrence nesting islands was caused by avian cholera and three that occurred off the coast of Cape Cod were attributed to acanthocephalans.

Avian Botulism at a New Site in Nevada.
In mid June 2004, personnel of the U.S. Fish and Wildlife Service (FWS) Las Vegas, Nevada Field Office reported mortality of waterfowl, shorebirds and an occasional songbird or upland game bird at a nature preserve encompassing secondary and tertiary wastewater treatment ponds. The facility includes 122 acres with 14 separate wetlands and no previous history of avian mortality. By the first FWS site visit on June 16, approximately 200 dead birds had been collected and deposited in a landfill by treatment plant workers. Three hundred to five hundred water birds remained at risk. The weather had been unusually hot (daytime highs >1000 F) for several weeks. FWS biologists collected two weak, lethargic ducks with drooping heads for diagnostic evaluation at the NWHC. At necropsy no significant gross pathological lesions were observed and botulism type C toxin was confirmed in blood from both ducks. The FWS biologists encouraged the treatment plant personnel to intensify their surveillance and carcass collection efforts. Over the course of the next month 100 more birds were collected. A liver culture from one bird contained Riemerella (Pasteurella) anatipestifer, the agent of New Duck Disease; however, no gross or microscopic pathological lesions consistent with that disease were observed in the duck.

Cyanide intoxication of songbirds detected.
For the second year in a row, cedar waxwing mortality in South Dakota appears to be linked to cyanide toxicity following ingestion of buds from Cotoneaster pyracantha shrubs. This thorny evergreen shrub grows 3-8 feet high and is native to southern Europe and western Asia. It is a favored ornamental because of the numerous white flowers followed by bright red haws. Toxicity can vary by the amount ingested and clinical signs include initial rapid respirations followed by slow breathing, anxiety, confusion, vomiting and dizziness. This year an estimated 30 cedar waxwings were reported in the Aberdeen, South Dakota area between May and June. In 2003, the timing of 200 cedar waxwing deaths was first correlated with their feeding in budding and flowering shrubs that contain cyanogenic glycosides. Analysis of tissues from birds in 2003 and 2004 found levels of cyanide were elevated but below the 1.0 ppm toxic dose. The combination of time between death and handling of samples could account for lowering of the tissues cyanide levels. Analysis of GI contents and plant samples by South Dakota State Veterinary Diagnostic Lab in 2003 and 2004 showed levels of cyanide >200 ppm the toxic range to all animals. In 2002, an estimated 100 waxwings died in the Aberdeen area from late May through July. It was suspected from field observations and necropsy examinations that the birds were poisoned but the connection to ingestion of Cotoneaster sp. was unknown and no cyanide tests were done. NWHC acknowledges the staff of the Sand Lake National Wildlife Refuge staff whose observation and collection of birds and plant materials over the past three years allowed this investigation to be completed.

For additional information please contact Dr. Scott Wright, USGS National Wildlife Health Center - Disease Investigations Branch Chief, at 608-270-2460 or Paul Slota, USGS National Wildlife Health Center - Support Services Branch Chief at 608-270-2420.