An update on the deer virus

By Patricia Guthrie


The virus that sickened and killed hundreds of deer across the San Juan Islands this summer appears to have tapered off with the cooler weather.

Known as adenovirus hemorrhagic disease (AHD) wildlife officials report receiving 112 reports of dead deer from San Juan Island and 218 reports from Orcas Island.

“The disease has likely had population-level impacts on San Juan and Orcas Islands, although the percent of population reduction is not known,” said Samantha Montgomery, communications manager with Washington Department of Fish and Wildlife.

A better idea of the degree of impact may come after the hunting season, she said. Black-tailed deer are considered overpopulated on San Juan, Orcas, and Whidbey islands, meaning there are too many for ecological and social balance.

“At this point, we have not received a public report of an AHD-related dead deer from San Juan Island since early August and the last public report of an AHD-related dead deer on Orcas occurred on Oct. 2,” Montgomery said.

The highly contagious virus only affects cervids, such as deer and elk. It doesn’t pose a risk to people, pets, or livestock.

In May, residents started reporting seeing dead deer with white foam at their mouths. The disease was confirmed in June after WDFW received laboratory results completed at the Washington Animal Disease Diagnostic Laboratory at Washington State University.

Suspected cases of AHD also came in from Blakely, Henry, Lopez and Stuart islands over the summer. Outbreaks of AHD have previously occurred in Oregon and California and in British Columbia on the Gulf Islands and Vancouver Island.

The virus can spread rapidly among dense populations of deer, although not all infected deer die. Fawns are most commonly affected, but all ages are susceptible. Death can occur within three to five days from the time a deer is exposed to the virus.

Signs of infection include rapid or open-mouth breathing; foaming or drooling at the mouth; diarrhea which is sometimes bloody; weakness; and emaciation.

To slow the spread of the virus, WDFW asks residents not to feed deer and to remove low-hanging bird feeders, salt licks, and supplemental water from yards. This prevents deer from congregating. When deer rely on natural food and water sources, they are more likely to remain spread out and away from each other — which could save their lives.

The virus is transmitted through bodily fluids, primarily blood, feces, and saliva, and infected materials can still transmit the disease after death.

Residents are advised to wear heavy rubber gloves when handling a deer carcass. There is no known cure or treatment for the virus.

People who see live or dead deer with signs of AHD are asked to report their sightings online through the reporting link on WDFW’s wildlife diseases webpage, For more information on AHD, go to WDFW’s AHD webpage at Updates are also available on the WDFW blog.