Epizootic Hemorrhagic Disease diagnosed in Colorado

Sep 21, 2012

Epizootic Hemorrhagic Disease (EHD) has been diagnosed in yak at two locations in Larimer County and one location in Alamosa County; these three cases have been confirmed by laboratory diagnostic tests at Colorado State University.

“We have not had confirmed positives of EHD in recent years but this is the time of year, in late summer and early fall, that we would expect to see cases,” said State Veterinarian Dr. Keith Roehr.

EHD is a viral disease that affects deer, cattle and, most recently, yak. Signs of EHC include fever, loss of appetite, weakness, respiratory distress, swelling of the tongue, and erosive lesions in the mouth.

The disease cannot be transmitted by direct contact and is spread by insects, most commonly midges or gnats.

“Occurrence of the disease will diminish as hard frosts kill the virus and virus-carrying insects. Until then, it is important for producers to practice insect control to help prevent the spread of the disease,” said Roehr.

Recently, cases in deer and cattle have been diagnosed in Nebraska and South Dakota. The deer population in Nebraska has seen a significant number of cases this year. Further investigation is ongoing to determine if the outbreak in Colorado may be tied to the Nebraska cases.

More than 40 cattle herds in southeastern South Dakota have exhibited signs of illness associated with the disease that has killed hundreds of whitetail deer in the area, State Veterinarian Dr. Dustin Oedekoven said. About 5 to 10 percent of the animals in a herd are infected, he said.

The disease is not fatal to cattle, but is deadly to the whitetail deer.

“Cattle aren’t getting it from the deer. It’s the biting little midge that carries the disease,” Oedekoven said.

South Dakota has confirmed 900 cases of EHD killing deer this year, according to Game, Fish & Parks wildlife manager John Kanta. Mule deer are more resistant to EHD than whitetail deer, he said.

Nebraska’s Game and Parks Commission reports that EHD is suspected in the deaths of more than 2,200 deer across the state, according to a news release.

According to State Veterinarian Dr. Dennis Hughes, the Nebraska Department of Agriculture has confirmed nine cases of EHD in cattle throughout Nebraska.

According to Hughes, the disease has been affecting Nebraska’s deer population since the 1970s and is transmitted from deer to cattle by biting insects called midges.

“This is an unfortunate disease that has no preventative measures or treatment options for affected cattle,” said Hughes. “The extreme hot and dry conditions that have persisted across Nebraska have contributed to the number of cases we are experiencing. The first frost should eliminate the disease-spreading midges.

“Because these cases aren’t confined to a particular area, we have been receiving many questions from both producers and veterinarians across the state,” Hughes said. “Therefore, we felt it necessary to share this basic disease information and urge producers to contact their local veterinarians if their animals are experiencing these symptoms.”

Other states, including Ohio, have also seen a rise in EHD in the deer population. Ohio Department of Agriculture’s Animal Disease Diagnostic Laboratory confirmed that of 20 samples, 13 deer had EHD.

State animal health official’s stress EHD occurs annually in deer herds across North America.

In Michigan, the disease has taken its toll on the deer population, concerning local hunters.

The disease has been in Michigan since the 1950s and cases of EHD have been reported in the state annually since 2006, although previous cases usually involve a small, secluded pockets of deer.

“Because of Michigan’s climate in fall, midges don’t do as well as they do in other states because of our frost,” said John Niewoonder, a wildlife biologist at Michigan Department of Natural Resources’ Flat River Gaming Area office in Belding.

“Before 2006, EHD was reported only twice since the 1950s. We have had hotter, drier summers lately, this summer especially, which is likely the cause of more of the outbreak we are seeing.”

As of Sept. 12, there was a record number 2,800 reports of EHD-related deer deaths. Last year’s total count was around 500, Niewoonder said.

A similar hemorrhagic disease called bluetongue has been known to occur throughout the U.S. and Canada, but should not be confused with EHD.

The disease is common in portions of the northern Great Plains and the southeastern U.S., and was first identified in 1955 in New Jersey.

The EHD virus does not affect people. While there is no direct treatment for the EHD virus, supportive care is important to enable animals to recover from the disease. — Traci Eatherton, WLJ Editor