The northern plains’ trend toward warmer autumns may delay frosts that kill disease-carrying midges, thus last year increasing the incidence of epizootic hemorrhagic disease. Typically seldom exposed to the disease, white-tailed deer populations in Montana and North Dakota have developed no antibodies to combat it and suffered particularly high losses in last year’s outbreak.
A warmer climate could assist a deer population’s recovery, however, as milder winters result in stronger deer and healthier fawnings.
An article by Brian McCombie, published in July’s issue of American Hunter magazine, describes last year’s outbreak of the virus which killed as much as 90 percent of deer along a 100-mile stretch of the Milk River in northeastern Montana. Deer in other regions of the country, from North Carolina to New Jersey to Indiana to Michigan, experienced unusually high incidences of the disease as well. Drought, another weather phenomenon associated with climate change, is suggested to have played a role in the virus’s spread in Kansas. Deer surviving infection develop immunity; consequently, Southern deer herds with greater exposure to the disease vector consistently exhibit resistance and suffer less morbidity from the virus.
Although white-tailed deer appear to be most susceptible to EHD, Mule deer, bighorn sheep, elk and pronghorn can also contract the disease. EHD causes symptoms similar to another virus, bluetongue, also carried by midges.