Wildlife disease experts warn that the prolonged drought affecting much of the nation will likely spur a substantial outbreak of enzootic hemorrhagic disease (EHD), reports the Wildlife Management Institute. According to experts at the University of Georgia's Southeastern Cooperative Wildlife Disease Study (SCWDS), wildlife managers in the entire Missouri River drainage as well as the Piedmont regions of North Carolina and West Virginia should prepare to see their white-tailed deer herds "get hammered" by this year's rash of EHD.

Transmitted by a biting fly, or midge, of the Culicoides genus, EHD is an often-fatal viral disease that primarily affects white-tailed deer, though it has been documented in mule deer and pronghorn. The disease produces hemorrhaging lesions in infected individuals, and is one of a family of viruses that include bluetongue and various other strains of hemorrhagic disease.

The parched condition of America's heartland has accelerated this year's spread of EHD by concentrating deer near watering sources where the midge breeds and seeks water itself. Higher deer densities in these areas further increase the disease's prevalence by allowing the midge to infect more animals at a faster rate.

While outbreaks of hemorrhagic disease occur every year, severe epidemics are relatively rare. According to SCWDS, 2007 marked the last large-scale EHD outbreak in North America. The Cooperative's Diagnostic Service documented an unprecedented 237 virus isolations, and the location of many samples showed that the disease was expanding beyond its historical range.

Preliminary sampling data released last week indicates that, though not spreading, the disease seems to be hitting the states along the Missouri River the hardest from the Montana/Canadian border to southern Missouri. In states like Michigan, the total number of EHD-related deer deaths since the 1970's has doubled in this year alone. Unfortunately, experts warn that the worst may be yet to come.

"EHD usually peaks between mid September and mid October," said Dr. David E. Stallknecht, researcher with SCWDS and Professor at the University of Georgia's College of Veterinary Medicine. "The onset of fall frosts will put a stop to the midges and most EHD transmission for this year." Until that time, noted Stallknecht, many deer populations may experience significant mortalities.

Fortunately for hunters and wildlife managers, EHD has never been shown to adversely affect deer populations in the long term. While herds may suffer high mortality in isolated locations, overall deer numbers are not generally affected by EHD. Data going back to 1955 demonstrates that EHD has long been a factor in annual white-tailed deer mortality and populations recover from severe episodes within a few years. Even in states hit the hardest by this year's EHD outbreak, wildlife agencies predict no broad loss of hunting opportunities for this fall's big game seasons. Hunters should be aware that in most areas, regulators "will not modify 2012 deer seasons in response to EHD losses" given that "deer populations typically recover quickly following past EHD die-offs."

In the months to come, hunters and recreationists should be prepared to see more than usual numbers of deer carcasses in areas traditionally affected by EHD. However, as the virus does not infect humans or pets, hunters should feel confident that they are not at risk from handling or eating venison or being bitten by a midge carrying the disease. (md)