SPRINGFIELD, Ill. – An acute, infectious virus has killed white-tailed deer in four Illinois counties and is suspected of causing the death of deer in five others, the state Departments of Agriculture and Natural Resources reported today.

Epizootic Hemorrhagic Disease (EHD), an often-fatal virus that causes high fever and severe internal bleeding, has been confirmed in Cumberland, Effingham, Fayette and Wayne counties, and is considered the probable cause of unexplained herd deaths in Macon, Pope, Sangamon, Shelby and Vermilion counties.

“All the confirmed cases have occurred in captive deer herds, but wild deer are included among the suspected cases where the cause of death hasn’t been determined,” State Veterinarian Dr. Colleen O’Keefe said. “One farm, in Effingham County, lost 17 of its 22 deer to the disease.”

EHD poses no risk to humans, according to Dr. O’Keefe. Other wild ruminants also are susceptible, including elk, mule deer, pronghorn antelope and bighorn sheep. Domestic animals such as livestock may become infected, but rarely exhibit signs of the disease or develop serious illness.

EHD is spread by biting midges, or gnats. The midges transmit the virus from infected to uninfected animals as they feed. There currently is neither a vaccine nor an effective treatment for the disease.

“The only viable way to control the virus is to control the insect population,” Dr. O’Keefe said.

EHD outbreaks typically begin in late summer or early fall and end with an insect-killing frost. The deaths this year were first reported the third week of July and have continued through the end of August. Officials believe the dry summer in central and southern Illinois, where the cases are concentrated, has contributed to the current outbreak. As shallow ponds and creek beds dry up, deer and insects are congregating around fewer bodies of drinking water, enabling the virus to spread rapidly.

"Local weather conditions can, in some instances, allow for a greater population of biting midges in a small geographical area," Dr. Paul Shelton, Illinois Department of Natural Resources Forest Wildlife Program manager, said. "This can allow the spread of EHD to be localized, causing a higher mortality rate in white-tailed deer in a specific region."

EHD was first identified in 1955 when several hundred white-tailed deer died in both Michigan and New Jersey. Since then, cases have been documented throughout the northern United States and southern Canada. The last significant outbreak in Illinois occurred in 1998, although a few cases normally are observed in any given year.

Symptoms develop about seven days after exposure to the virus and include loss of appetite, excessive salivation, muscle weakness, lameness, depression and a rapid pulse and respiration rate. Eight to 36 hours after the onset of symptoms, animals enter a “shock-like” state, become prostrate and die.

Farmers with ill deer should not assume the animals are infected with EHD, even if they are exhibiting classic symptoms. A veterinarian should be called to give the deer a check-up. If the animal dies, the Illinois Department of Agriculture’s animal disease laboratories in Centralia and Galesburg will perform a post-mortem exam to determine the cause of death. The fee for this exam ranges from $40 to $100, depending upon the level of testing that is required.

Citizens or hunters who witness a deer exhibiting signs of EHD are urged to call their local conservation office.