(e) = estimate, * = morbidity and mortality

California Dept. of Fish & Game-Wildlife Invest. Lab (CA); Centers for Disease Control, Ft. Collins, CO (CDC); Colorado Division of Wildlife (CO), Connecticut Ag. Exp. Station & Univ. of Connecticut (CT); Illinois Dept. of Nat. Res. (IL); Live- stock Disease Diagnostic Center (KY); Louisiana Game & Fish (LA); Nat'l Wildlife Health Center (NW); New Jersey Dept. of Fish & Wildlife (NJ); New York State Dept. of Env. Cons. (NY); Purdue Diagnostics Lab (PD); Southeastern Cooperative Wildlife Disease Study (SC); US Geological Survey (GS), Washington Dept. of Fish & Game (WA), and Wisconsin Dept. of Nat. Res. (WI).

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

WNV 2000
West Nile virus (WNV) is a cause of wildlife mortality in the eastern US again this year. WNV is an arthropod- borne virus that had never been reported in the Western Hemisphere until the fall of 1999 when wild birds (primarily crows), horses, and people were affected in an outbreak in the greater New York City (NYC) area. This year, WNV was first detected in wild birds found dead the third week of May in southeastern New York and northeastern New Jersey and mortality in wild birds has been ongoing. Horses and people were affected again this year also. This year's outbreak is expanded both geographically and in the number of species found infected with WNV when compared to last year's outbreak.

Wild mammals were first found positive for WNV in August this year. Initially, bats found alive in private homes were submitted for rabies testing and then subsequently tested for WNV after being found rabies negative. A total of 25 wild mammals including bats, raccoons, chipmunks, and squirrels were found infected with WNV in the state of NY. A WNV positive skunk was found in CT. It appears that at least some of the bats found positive for WNV are dying of WNV and it is unknown whether these species are incidental hosts or if they are capable of transmitting WNV through a mosquito vector. At least 14 species of mosquitoes were found positive for WNV including both mammal and bird feeding species and species active at dawn and dusk, and during the day.

Amphibian Mortality/Morbidity
Chytridiomycosis, epidermal infections by the pathogenic chytrid fungus, Batrachochytrium dendrobatidis, was detected in multiple species of frogs, toads and salamanders, including tadpoles, larvae, neotenes and adults from 6 states. In three states (MN, NC & TX) this was the first detection of the pathogenic chytrid fungus. In 3 states chytridiomycosis had been previously diagnosed in amphibians in 1999 or previous years. Amphibian mortalities were attributed to the chytrid fungal infection only in adult (post-metamorphic) frogs and toads, while the chytrid infections in tadpoles and salamanders were considered incidental findings. Although the chytrid infections probably were subclinical cases in the salamanders, at two sites, it was reported that sympatric frogs and toads had suffered marked population declines. These findings provide further support to the theory that the pathogenic chytrid fungus is an important etiology in mortality events and may contribute to population declines in adult frogs and toads.

Iridovirus epizootics were considered the cause of mortality events in 9 amphibian species in 6 states. For the first time, mortality events attributable to iridovirus infections were observed in marbled salamanders and spring peepers in 2000. In addition, mortality events that simultaneously affected both ranid tadpoles and salamanders were observed at casualty sites in three states (MA, MN & NC). At two sites, mortality events have recurred annually for at least 3 consecutive years. Affected life stages were usually tadpoles, larvae, neotenes or recent metamorphs. Infected frogs and salamanders presented a variety of gross abnormalities, including hyperemia and petechiae in the ventral skin, skin ulcers, hydrocoelom, and mild focal ventral dermal edema to very severe generalized dermal edema of the body and limbs. All isolated iridoviruses are believed to be the genus, Ranavirus, in the family, Iridoviridae, but confirmatory molecular analyses are pending.

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.