Blacktailed deer are turning up dead in several rural Jackson County communities, and wildlife officials believe a deadly disease that decimated area herds more than a decade ago is back.
Biologists Tuesday learned they had their first confirmed case of the naturally occurring adenovirus from a deer found dead last week off Griffin Lane, but several reports of similar deaths have come in recently in Jacksonville, Eagle Point and elsewhere.
The deaths are occurring at a rate not seen since 2002, when more than 1,000 blacktails were estimated to have died that summer and fall, according to the Oregon Department of Fish and Wildlife.
"We've had deer die in the past 10 years that we thought were from adenovirus, but now we're seeing a lot of dead deer," said Mark Vargas, ODFW's Rogue District wildlife biologist in Central Point.
"We know it's here, and now we know we have another outbreak," Vargas said.
Adenovirus outbreaks tend to happen during hot and dry months. They have been associated with people leaving food and water for animals, which causes unnatural congregations of blacktails and other creatures, but the cause of the recent outbreak has not been determined, Vargas said.
The virus can spread easily — such as breathing air from an infected animal — so water buckets and grain piles placed by well-intentioned landowners can turn into viral hot spots that can kill groups of deer in days.
"Without a doubt, I firmly believe that it passes the virus faster," Vargas said. "Wildlife don't need food or water."
First diagnosed in Northern California in the mid-1990s, adenovirus hemorrhagic disease is believed to have been responsible in the late 1980s for killing hundreds of deer whose deaths originally were attributed to a different disease known as bluetongue.
A smaller outbreak occurred locally in 2009, as well.
Infected deer can suffer from bloody diarrhea that can scour the animal or cause mouth lesions that keep it from feeding.
In some cases, the deer suffer massive internal hemorrhaging. In other cases, field necropsies have revealed a liter or more of liquid in the lungs of infected animals.
Humans and pets are not considered vulnerable to the virus. While similar strains of adenovirus affect cattle and sheep, there are no known instances of the virus spreading from deer to other species.
As with past outbreaks, most of the dead blacktails found so far have been urban deer or those living near rural residences, Vargas said.
Vargas said biologists want to hear from landowners who find dead deer, but agency biologists will not test all the carcasses or remove them.
People who find dead deer should either take them to the landfill or bury them, Vargas said. If inside city limits, they should call their city public works department, he said.
Reach Mail Tribune reporter Mark Freeman at 541-776-4470 or firstname.lastname@example.org.