Hemorrhagic disease suspected in Bighorn Basin die-off
Wyoming Game and Fish Department biologists suspect hemorrhagic disease – either epizootic hemorrhagic disease (EHD) or bluetongue – has killed a number of white-tailed deer in the eastern Bighorn Basin since mid-July. Due to the difficulty in locating carcasses and the broad area affected, the exact number of deer potentially affected by the diseases cannot be determined.
EHD and bluetongue are different viruses that are spread by biting gnats. EHD and bluetongue primarily affect white-tailed deer but can also infect pronghorn antelope, elk, and mule deer. Variants of the diseases can affect species such as bighorn sheep and some domestic animals. Affected deer are often found dead. Other symptoms include loss of appetite, extreme weakness, unwillingness to rise, lameness and bleeding or swelling of head, neck, tongue, or eyes. Infected animals usually die in late summer and fall, often near water.
EHD or bluetongue die-offs are a common occurrence in many states. Lack of water sources and rapidly drying ponds tend to concentrate deer in areas where gnat populations are high and accelerate the spread of the diseases. A confirmed diagnosis requires laboratory identification of the virus from tissues including lung, spleen, lymph nodes, and blood. Samples from deer carcasses found in the Bighorn Basin this summer have been sent to the Wyoming State Veterinary Laboratory in Laramie for testing.
Drought conditions led to hemorrhagic disease outbreaks and the loss of white-tailed deer across some areas of eastern Wyoming last year and very significant losses in South Dakota and Nebraska.
“We suspected a few cases last year along the Bighorn River, and it appears a die-off is occurring again in some locations,” said Greybull Wildlife Biologist Tom Easterly. “However, the disease is endemic in many places in Wyoming and we probably experience some level of die-off most years. The weather is a big factor and since this summer has been hot and dry in the Bighorn Basin, the conditions are optimal for a major outbreak. Typically, the spread of disease is reduced significantly after the first heavy frost of the year.”
The Montana Fish, Wildlife and Parks have also received reports this summer of dead and dying white-tailed deer along the Bighorn and Yellowstone rivers and suspect EHD or bluetongue to be the cause.
In recent weeks concerned citizens have contacted Game and Fish about dead or dying deer. “I have been fielding a lot of phone calls about sick and dead deer in Big Horn County,” said Lovell Game Warden James Hobbs.
There is no human health concern from hemorrhagic disease. Humans cannot contract the disease and neither can most other wildlife. Mule deer occasionally get the disease but are generally insulated from the infection because they do not tend to inhabit the environment of the gnats. If you see a sick deer, contact your local warden or biologist.
EHD was first identified in Wyoming in the Black Hills in 1957. At that time, a significant die-off of deer occurred north of Newcastle on Oil Creek.
Contact: Tim Woolley 307-527-7125 or Tom Easterly 307-765-2742 for more information. F
–Wyoming Game and