Francis Skalicky writes in the News-Leader about the effect of drought on deer, making them increasing susceptible to Epizootic Hemorrhagic Disease (EHD). Chronic Wasting Disease (CWD) is a neurologic disease which gets a lot of press. Chronically ill deer which slowly loose weight, act listless and walk around without their usual alert behavior are more likely to attract our attention.
EHD causes defects in blood clotting as well as blood vessel damage. The resultant internal hemorrhage creates a variety of more rapid symptoms which are indistinguishable from bluetongue disease.
"White-tailed deer develop signs of illness about 7 days after exposure. A constant characteristic of the disease is its sudden onset. Deer initially lose their appetite and fear of man, grow progressively weaker, often salivate excessively, develop a rapid pulse and respiration rate, and fever (affected animals frequent bodies of water to lie in to reduce their body temperature) and finally become unconscious. Hemorrhage and lack of oxygen in the blood results in a blue appearance of the oral mucosa, hence the name 'bluetongue'. Eight to 36 hours following the onset of observable signs, deer pass into a shock-like state, become prostrate and die."
Since the virus dies within 24 hours in the deer's carcass, it doesn't pose a transmission risk. There is no risk of human disease although no one should harvest a sick deer anyway.
Comprehensive EHD information is available at michigan.gov/dnr.