(e) = estimate * = morbidity and mortality

California Department of Fish and Game-Wildlife Investigations Laboratory (CFG); Centers For Disease Control, Ft. Collins, CO, (CDC); Colorado Division of Wildlife (CO); Idaho Department of Fish and Game (IFG); National Wildlife Health Center (NW); New York State Department of Environmental Conservation (NY); Southeastern Cooperative Wildlife Disease Study (SC).

Written and compiled by Kathryn Converse, Kimberli Miller, Linda Glaser, Terry Creekmore, and Audra Schrader, National Wildlife Health Center (NWHC). To report mortality or if you would like specific information on these mortalities, contact one of the following NWHC staff: Western US Kathryn Converse; Eastern US--Kimberli Miller; Hawaiian Islands--Thierry Work. Phone (608) 270-2400, FAX (608) 270-2415 or E-mail kathy_converse@usgs.gov. National Wildlife Health Center, 6006 Schroeder Road, Madison, WI 53711.

Quarterly Mortality Reports

On September 24, the Centers for Disease Control (CDC) announced the isolation and identification of the West Nile virus (WNV) from birds collected in New York City. West Nile virus is an arthropod-borne virus closely related to St. Louis encephalitis (SLE) virus, a known virus infection of birds in the United States which occasionally causes human cases and epidemics. The West Nile virus has never been reported in the United States or any area of the Western Hemisphere prior to this isolation. Birds are the natural hosts for this virus and the virus is transmitted from birds to other animals, including humans, through the bite of mosquitoes. The virus is not directly transmitted between humans and is not known to be transmitted from birds to humans or to other animals without the arthropod vector.

American crows appear to be especially sensitive to this disease with mortality in a 14 county area of New York City (including counties in New Jersey) estimated to be in the thousands. Fish crows are also dying of WNV. West Nile virus has been identified in 17 native American bird species although it has not been determined to be the cause of death in all these species. Each of the states of New Jersey, Connecticut, and New York are examining the bird carcasses found within their borders for WNV. The USGS National Wildlife Health Center has recruited submission of carcasses, primarily crows, from states on the Atlantic coast (outside of NJ, CT, NY) for WNV testing. One crow from Baltimore, MD was found to be positive for WNV during this surveillance effort. Carcass submission and testing for WNV is ongoing and surveillance is planned through the winter. Selected specimens from probable WN virus positive crows submitted from new locations will be shipped to CDC for confirmation. Concurrently, USGS and CDC will be collaborating with Dr. Ward Stone (New York Department of Environmental Conservation), New York City and New York State Public Health officials, and the U.S. Fish and Wildlife Service to conduct field investigations in the New York area. Researchers will attempt to determine the wildlife species involved, the geographic and temporal distribution of the new virus in bird populations, and where the virus may be expanding beyond the currently reported sites. There is concern that if migratory birds are infected, the virus will move farther south during fall migration.

Type E botulism was confirmed in gulls collected during mortality of 230 ring-billed, greater black backed and herring gulls since late July on Presque Isle State Park in Erie, Pennsylvania. Other species implicated in the mortality include ducks and loons, however these species have not yet been tested for the toxin. Botulism type E has been the cause of bird mortality in the Great Lakes in 1963, 1964, 1965, 1968, 1970 1976, 1977, 1980, 1981, and 1983. All of the bird moralities occurred in the autumn, except in 1980, and it is thought that eating fish exposes the birds to the toxin. The Canadian Cooperative Wildlife Health Center has confirmed botulism type E mortality in birds collected from two ongoing mortality events. Over 200 common loons, grebes, diving ducks, and ring-billed, herring, and Bonaparte's gulls have died along the northern shore of Lake Erie in Ontario, Canada between Point Pelee National Park and Rondeau Provincial Park, and several hundred red-throated loons, grebes, mergansers, diving ducks, and ring-billed and Bonaparte's gulls are reported to have died along the southeastern part of Lake Huron near Kettle Point and Grand Bend.

Waterfowl mortality was reported at the Benton Lake National Wildlife Refuge in late July. Botulism was the suspected cause of death, however many of the birds that were collected were thin. All of the birds initially submitted to the NWHC were emaciated and several had pneumonia and/or an airsacculitis. Cultures submitted to the National Veterinary Services Laboratory in Ames, Iowa were positive for chlamydia. A follow-up field investigation of this mortality event confirmed the presence of chlamydia in samples taken from migratory birds trapped on the refuge. This is the first reported chlamydiosis mortality in migratory waterfowl in the United States.

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.