CHEYENNE, Wyo. (AP) — A disease is killing dozens of white-tailed deer in Wyoming and Montana.

Wildlife officials say the disease causes internal bleeding and is either epizootic hemorrhagic disease or bluetongue. Tests are being done to determine which virus is the cause.

Neither virus poses a risk to humans. White-tailed deer are the usual victims but hemorrhagic disease also can infect pronghorn antelope, elk and mule deer.

People in recent weeks have come across dozens of dead and dying deer in the Bighorn Basin in north-central Wyoming and from the Great Falls area to north of Chester in north-central Montana.

Hemorrhagic disease is native to the region and outbreaks are fairly common. Biting gnats spread the viruses. Outbreaks tend to peak as dry weather causes deer and gnats to congregate near water.