Just imagine the heartbreak Tommy Corder experienced last year after finding nearly 20 deer that had died from bluetongue in a small area in Wayne County, Kentucky. Corder found four nice bucks including a giant 18-pointer he had been hunting for the past three years. Last season, states like Indiana, Illinois, Kentucky, Tennessee and were hit hard by bluetongue virus and a number of good bucks were unfortunately taken out of the herd. This disease is nothing new, but in ’07 it seemed to have taken a major toll on deer populations.
Recently, I spoke with deer biologist David Yancey about this deadly disease to better understand the causes and overall impact it can have on the herd. Yancey explained that bluetongue and epizootic hemorrhagic disease (referred to as “EHD”) are two very similar viral diseases of hoofed animals. They are so similar that the only way to tell which one you are dealing with is by conducting laboratory work. This is why both diseases are collectively referred to as hemorrhagic disease. Hemorrhagic disease is spread from deer to deer by tiny biting flies. This is the sole method of disease transmission and deer can not contract it by simply drinking the same water, feeding together, or through daily interaction.
EHD-infected deer may exhibit a swollen head, neck, tongue, or eyelids and they might also have difficulty breathing. Afflicted deer will usually be listless and feverish, which explains why dead or dying deer are often found near water such as ponds and creeks. According to Yancey, the high death toll from bluetongue last year was believed to be drought related. The theory is that last summer’s drought across many states forced deer to concentrate around remaining water sources making it easier for the flies to spread the virus. Also, as water supplies dried-up it left behind shallow-water holes that provide ideal conditions for Culicoides reproduction. When you look at the map of the 2007 summer/fall drought it matches up perfectly with the 2007 EHD outbreak map.
EHD outbreaks end with a frost that kills the flies that spread the virus and many areas experienced warm temperatures late into the fall. Statistics are still being examined by many states, but unfortunately a lot of healthy deer died last season from the disease.