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#06-263 October 2, 2006  

Deer hunters should not confuse chronic wasting disease

 

with hemorrhagic disease

Although chronic wasting disease represents a significant threat to infected deer and elk populations, there is no evidence that chronic wasting disease occurs in South Carolina, according to the state natural resources agency.

However, it has been documented in wild deer and/or elk herds, as well as, captive or farmed herds in a number of Western and Northeastern states. The S.C. Department of Natural Resources (DNR) has been conducting surveillance for chronic wasting disease in South Carolina since 1998, and this surveillance will continue and likely be increased due to the spread of chronic wasting disease in the West and Northeast.

But hemorrhagic disease is the most significant disease of deer in the Southeast, according to Charles Ruth, DNR Deer/Turkey Project leader. Each year during late summer and early fall as deer hunters begin their activities, DNR is contacted about an occasional sick or dead deer that is found. Although there are a number of diseases that can cause sickness and death in deer, the most likely cause during the late summer and fall is hemorrhagic disease. The disease is caused by certain viruses that are transmitted by biting midges or gnats, commonly called no-see-ums. The seasonality of the disease is related to the life cycle of these insect vectors since they thrive during the warmer months in the Southeast. Simply put, the better the conditions are for midges, the greater the chances are that hemorrhagic disease will be spread to deer.

In addition to being seasonal, hemorrhagic disease appears to flair up about every three to five years, Ruth said. This is probably related to the fact that once deer are exposed to the disease they are more resistant to it. Therefore, if you have disease one year the deer become exposed or inoculated to the disease and you do not see much disease activity until there is turnover in the deer population. After several years you are dealing with another group of deer and their systems are “naive” to the disease. The last time there was significant hemorrhagic disease activity in South Carolina was in 2002, therefore, disease activity could be relatively high this year.

Symptoms of hemorrhagic disease include poor physical condition, sloughing hooves, abrasions or sores on the brisket and legs, and ulcerations on the mouth, tongue, and rumen (stomach). Actual verification of the disease must be through laboratory analysis of blood or certain other tissues. DNR has monitored for hemorrhagic disease since about 1980 through an effort directed by the Southeast Cooperative Wildlife Disease Study, which is part of the School of Veterinary Medicine at the University of Georgia. Through this process, the Southeast Cooperative Wildlife Disease Study has determined that hemorrhagic disease is common over most of the Southeast. The severity of hemorrhagic disease varies annually and geographically with cases being mild and scattered in some years while in other years significant outbreaks and mortality can occur.

Deer likely die in South Carolina each year from hemorrhagic disease, however, there is no indication that a major outbreak has occurred in the state since the mid 1970s, according to Ruth. The disease is part of life for deer in the Southeast and fortunately, it appears that Southeastern deer have acquired some immunity to the disease. Northern deer, on the other hand, are not exposed to the disease as frequently since the insect vector is not as common in cooler climates. For this reason, significant outbreaks and mortality from hemorrhagic disease are more likely in Northeastern deer populations.

Although it is important for hunters to report sick or unexplained dead deer to the DNR, there is little that can be done to prevent hemorrhagic disease since it is spread by insects rather than from deer to deer. As with any recommendation for disease prevention, DNR encourages hunters to keep deer populations at reasonable levels, which leads to overall good herd health. The disease does not pose a threat to hunters, however, hunters should not consume deer or any other game that appears sick or in poor condition.
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