Chronic Wasting Disease and West Nile Virus: Are Either a Threat to the Turkey Hunter?
By: Dr. James Earl Kennamer
These days, it is hard to pick up an outdoor magazine without seeing some reference to chronic wasting disease. But that's a concern for deer hunters, right? The answer is yes and no. As for turkey hunters, there is both good news and bad concerning CWD. The good news is there is no evidence, as of today, that the disease can be passed to either turkeys or humans. But, if the disease is not controlled and continues showing up in wild populations, it could change deer and elk management programs, and possibly turkey movement programs, in the future.
CWD is very similar to mad cow disease and affects the central nervous system of deer and elk. For animals that contract the disease, CWD is 100-percent fatal.
As of August 2002, the disease has been found in free-ranging and captive (pen-raised or confined) deer or elk in Colorado, Montana, Oklahoma, Minnesota, Wyoming, Wisconsin, New Mexico, Nebraska, Kansas and South Dakota. It has also been found in captive elk in the Canadian provinces of Alberta and Saskatchewan. To date, mule deer, white-tailed deer and elk are apparently the only animals affected.
According to the Southeastern Cooperative Wildlife Disease Study based at the University of Georgia's College of Veterinary Medicine, CWD was first recognized in the 1960's as a nervous system disorder in mule deer held in several wildlife research facilities in Ft. Collins, Colo.
Unlike mad cow disease, CWD is not a food-borne disease. Originally, researchers thought CWD was due to nutritional deficiency, but apparently, it is passed from one animal to another through saliva or feces, either from direct contact or ground contamination. Affected animals may show poor body condition, walk in circles and carry their head and ears lowered. As the disease progresses and in terminal stages, excessive drinking, urinating, salivating and drooling are common.
Wildlife agencies in states that have been affected by CWD are taking aggressive action to try to prevent its spread. In Wisconsin, a CWD Eradication Zone has been established in the affected area to combat the disease. In this area, the goal is to reduce the deer population as much as possible to decrease the possibility of infected animals spreading the disease by contact with healthy deer.
Wisconsin has also enacted a statewide ban on feeding and baiting deer, which tend to concentrate deer in small areas and help make the spread of CWD more likely. It is probable that other states affected by CWD will enact similar bans. The Colorado Wildlife Commission recently enacted carcass transportation regulations, which will affect movement of deer and elk carcasses from the CWD-endemic portion of the state. Several states and provinces are thinning wild herds and buying out deer and elk game farms to eliminate the animals.
It is absolutely critical that movement of captive animals, both legal and illegal, be carefully monitored for CWD, or the future of big game hunting will be in jeopardy.
Effects for the Turkey Hunter
How does CWD affect the turkey hunter? Many turkey hunters are also deer hunters, and may be affected directly in that respect if CWD enters their state's deer herd, but there are other effects as well. Most states that are affected by CWD are also regulating or forbidding the movement of captive deer and elk in or out of the state. At present, 49 of the 50 states have enacted new regulations that range from additional testing requirements to the banning of all animal imports. There is a great concern that illegal trade of deer and elk may spread the disease into unaffected areas. If CWD continues to spread, and many wildlife biologists are concerned that it will, we may see widespread prohibition on the movement of game animals, including turkeys.
While, as previously stated, CWD does not affect turkeys, state game agencies and state veterinarians may become alarmed enough, because of its potential effect on their deer and elk populations, to prohibit the interstate movement of turkeys and other game animals, which would effectively end turkey restoration efforts in areas that depend on out-of-state birds for trap and transfer. While we don't know this will happen, it is certainly an issue that will demand our close attention for some time to come.
Look for updates on this and other CWD topics in future issues of Turkey Call magazine and other NWTF publications. More detailed information, breaking news and a listing of state regulations may be found on the website for the Chronic Wasting Disease Alliance (www.cwd-info.org).
West Nile Virus
In addition to chronic wasting disease, West Nile virus is a daily topic with the news media. WNV was first recognized in North America in New York City during the summer of 1999. Prior to that, the virus had been documented in Africa, Europe, the Middle East and parts of Asia. It is not known where the North American strain originated, but it is genetically similar to the Middle Eastern strain. Since 1999, the disease has spread southward and westward and has now been found in all states east of a line from Arizona to Idaho.
According to the Centers for Disease Control and Prevention, WNV is transmitted to humans by mosquitoes. Most infected humans and animals are not severely affected, but some birds, especially crows and blue jays, are very susceptible to the disease and often die when they become infected. Horses are particularly susceptible to the disease, and a vaccine for them is now available. Wild birds that appear healthy have a very low likelihood of carrying the virus. Nonetheless, sick or dead birds may harbor significant levels of WNV that could pose a threat to human health. Handling sick, wild animals is always discouraged, regardless of the cause of disease.
According to Bob Eriksen, NWTF northeastern regional biologist, testing has shown that turkeys are unlikely to be greatly affected by WNV or to serve as a reservoir for transmission of the disease to other species. In a series of tests by researchers at the Southeast Poultry Research Laboratory, domestic turkey poults were inoculated with a dose of WNV large enough to cause infection and were observed and tested. All of the poults developed the virus, but none showed severe symptoms and none died from the disease. In addition, the level of the virus in the poults' blood was too low to allow the disease to be transmitted by mosquitoes to other animals. There was no transmission from the infected poults to others in the same pen, and the experts have concluded that there is little potential for WNV to become a major problem in either domestic or wild turkeys.
A few wild turkeys have tested positive for WNV, but none are known to have died from it. Turkey hunters should not worry about eating any wild turkey that was acting normally when harvested. Your chances of contracting any disease from properly cooked wild game are very low.
What can you do to avoid contracting WNV? The CDC states that while the chances are very low that any one person will become ill from a mosquito bite, the best prevention of WNV is to avoid mosquito bites altogether.
According to the CDC's website (www.cdc.gov), persons exposed to mosquitoes should use repellents containing DEET, wear long sleeve shirts and long pants when possible, consider staying indoors at the peak mosquito times of dawn, dusk and early evening and limit the number of places that mosquitoes can breed by eliminating standing water sources around the home. For the turkey hunter, staying inside is not an option, but repellents and protective clothing can effectively reduce mosquito bites.
Refer to the CDC website for more detailed information on the effectiveness of different mosquito repellents and protective clothing. Watch future issues of Turkey Call and other NWTF publications for updates on West Nile virus.