An estimated 200 wild deer, mostly fawns, have died after being stricken by an unknown virus in suburban and remote mountain areas of Northern California, state wildlife officials reported Friday.
Many fawns had no symptoms when they died, while others have shown signs of weakness, staggering and excessive salivation.
Officials with the California Department of Fish and Game are unable to estimate the number of deer that have died of the virus, which was recently discovered by the agency's veterinarians. But "the death toll in some areas is significant," the agency said.
In one area of California's Nevada County, up to 75 carcasses were found.
"The Department of Fish and Game is working to determine the range of the disease and the extent of losses," said Bill Clark, coordinator of the agency's Wildlife Investigations Laboratory, who estimated that 200 animals were involved.
Most of the deaths occurred in suburban residential areas, although some deer were found dead in mountain areas.
State wildlife experts have found a virus in several of the youngest fawns that damages blood vessels, leading to respiratory failure and stomach ailments.
Veterinarians and pathologists with the Department of Fish and Game, UC Davis and the California Diagnostic Laboratory System are collecting carcasses and trying to isolate the deadly virus. They suspect it is an adenovirus, which frequently kills young animals of other species but had not previously infected deer.
Officials said it appears to pose no threat to humans, but they cautioned people to avoid feeding wild deer, which can cause overpopulation in some areas and allow disease to spread more quickly.