Bluetongue, a disease that causes animals to bleed to death internally, is hitting antelope and white-tailed deer in southeastern Montana.

Fish, Wildlife & Parks officials say the disease, which is spread by a biting gnat, has been found in antelope in the Melstone-Sumatra-Ingomar area and white-tailed deer along the Yellowstone River.

Reports of the dead animals began about three weeks ago. FWP issued a news release Thursday afternoon stating that "several hundred" animals had died.

"It seems to be centered in Musselshell, Treasure and Rosebud counties," said John Ensign, head of wildlife for Fish, Wildlife & Parks in Miles City. "We also are seeing dead whitetails along the Yellowstone from Hysham to Miles City. We haven't sent any of those off (to the state) but that looks more like EHD (epizootic hemorrhagic disease), but it could be bluetongue."

There also have been reports of dead elk in Musselshell County, but FWP has not tested any of those animals.

"We found a dead elk or two but there was no indication of what it was from," said Ron Aasheim of FWP in Helena. "Elk are susceptible."

Bluetongue, also called catarrhal fever, most often hits sheep and less frequently cattle, goats, buffalo, deer, dromedary camel and antelope. Lab tests confirmed the disease killing the antelope is bluetongue, which often is confused with epizootic hemorrhagic disease or EHD. FWP expected lab results of the antelope to show EHD instead.

"The signs are similar. Animals exhibit the same symptoms and signs," Ensign said.

In 2001, an outbreak of EHD swept through Eastern and Central Montana, reaching as far west as the dry fork of the Marias River. That outbreak killed dozens of white-tailed deer.

How it works

A gnat spreads the virus, which has a life cycle of about seven to 10 days, meaning it takes that long for an animal to exhibit symptoms of the virus. The animal typically dies within 24 hours after showing symptoms, Ensign said.

"Typically, you will see the critters that look distressed. They are breathing heavily, panting and show signs of weakness. The virus breaks down the capillary walls and they bleed to death internally," he said.

Ensign said FWP has received reports from landowners and archery hunters of at least 100 dead antelope in the Ingomar area but he thinks there is probably quite a few more.

While severe outbreaks can claim up to 75 percent of the animals in a particular area, Ensign said he doubts this recent case will come to that.

"I don't know if we have ever had 50 percent mortality," he said. "It is really hard to quantify. What is going to make this go away is a good, hard frost that will kill the biting midges that carry the virus."

"If (it) continues and there is no frost, yeah, the scale can get very large," added Quentin Kujala, FWP's head of wildlife biologists in Helena.

In the field

Dan Clifton of Sumatra said he has seen 15 to 20 of the dead animals. A retiree who helps neighboring ranchers check water, Clifton is outdoors almost all day every day.

"They are all ages - bucks, does, fawns," he said. "It seems funny that wherever you find one there is another not very far away.

"I found one and I drove over to it. It got up and walked 10 to 15 feet and staggered and then went down. The next day it was dead. You see them lying all over," Clifton said. "There is no particular type of area."

FWP gets reports of EHD every year. Ensign said whitetails are especially susceptible, adding that most of the time the dead animals are found near water.

"They are bleeding to death and they are around water because they are trying to bring back the blood volume. Every five to seven years we have major outbreaks," he said. "We find it on the Yellowstone by Hysham and sometimes down to Glendive and occasionally on the Tongue."

For hunters

Antelope archery season opened Sept. 1, and antelope rifle season opens Oct. 7. A hard frost should occur by opening day of the rifle season.

"By the time your rifle hunters get out there, the outbreak should have run its course. By that time, you have one of those good hard frosts that knocks the stuffing out of biting gnats," Ensign said.

Hunters should know that both bluetongue and EHD have no effect on humans, Ensign said.

"Contact with that and consumption of meat is not going to hurt you," he said. "When animals look sick, it is for a real short period of time. If you are out there and looking at a sick animal, don't shoot it."

If a hunter were to shoot an infected animal, he would notice the tongue has turned blue or there might be blood at the animal's orifices.

George Woodhall, retired game warden and Stanford businessman who has hunted antelope around Ingomar for the past 25 years, said he still plans to hunt there.

"I am going to be very careful. If they don't look plumb healthy, I am going to pass them up," he said.

Ensign said that as with any disease outbreak, the more dense the animal population, the easier it spreads. He said antelope numbers in Region 7 have been as much as 25 percent higher than the long-term average population.

"The last couple of years we have had extremely mild winters," Ensign said. "We haven't had much for overwinter mortality."

Sheep dying too

It was reported earlier this week that State Veterinarian Dr. Marty Zaluski prohibited sheep producers in Musselshell County transporting their animals for the next 30 days because of an outbreak of bluetongue.

Zaluski authorized the hold order Monday in an effort to reduce potential transmission of the virus.

About 100 sheep in Musselshell County have died in the past two weeks, according to the Montana Department of Livestock. Several sheep initially tested positive for the virus in a screening test, and once white-tailed deer were tentatively diagnosed, Zaluski decided to protect other livestock with the order.

Vaccinations are available to livestock producers, but Ensign said there isn't much officials can do in the case of wildlife.

"You have to let it run its course," he said.