When cold weather kills insects, the spread of hemorrhagic disease ends. Hemorrhagic disease is always present in the whitetail population to some extent, and several small, localized outbreaks are reported in Nebraska in the summer and early fall nearly every year. Deer surviving an outbreak develop an immunity that protects them from the sub-type of virus they had. Deer with Hemorrhagic Disease Deer with hemorrhagic disease seem listless and disoriented, and a high fever and the resulting thirst keeps them near water. Other external symptoms include swelling of the head, neck, tongue and eyelids, and difficulty in breathing.
Internal examination shows lesions, swelling or hemorrhage of the heart, lungs and other organs.
Laboratory tests to identify hemorrhagic disease virus require that samples be taken from a living or newly dead deer, since the virus cannot survive outside a living host animal or the insect carrier. While whitetails are most vulnerable to hemorrhagic disease, it also affects mule deer, pronghorn antelope and bighorn sheep. Humans are not at risk. The effects of bluetongue and EHD on cattle and goats can range from benign to debilitating, but the diseases are seldom fatal. Sheep are not affected by EHD, but can be made seriously ill by bluetongue.