DEAR DR. FOX: I just read your article on the possibility of chronic wasting disease (CWD) from deer being transmitted to humans. While it has not crossed that barrier yet, it goes far deeper than that.
CWD has been found in plants, such as farm crops, and is transmittable to animals that eat these plants. These crops get harvested and made into various breads, cereals, soybean products -- all sorts of things that get sent to market and then to us. So technically, CWD is in our food chain already, not just in venison.
There is no cure for CWD at this time. If it jumps that barrier, then what? -- M.S., Erie, Pennsylvania
DEAR M.S.: As I state in my post about CWD on my website, many experts contend that chronic wasting disease was initially spread from captive deer in Colorado, some of which were transported to other states. State wildlife management practices that foster large deer populations for hunters have exacerbated the spread of CWD, as has the elimination of wolves, which help control deer populations and disease. The white-tailed deer population, now estimated at some 30 million across the U.S., is also impacting forest regeneration.
In the midst of the COVID-19 pandemic, we face another issue involving deer. A recent study of the incidence of SARS-CoV-2 in white-tailed deer by the USDA's Animal and Plant Health Inspection Service discovered that 33% of 481 blood samples collected from January 2020 through March 2021 from deer populations in Illinois, Michigan, Pennsylvania and New York tested positive for this coronavirus. In another study, samples taken early this year from eight white-tailed deer in Ohio contained SARS-CoV-2. How the deer became infected is not known, but it could have been from close contact with COVID-19-infected people on deer farms and in parks. Or possibly from leftover picnic items and human feces in public parks and campgrounds.
White-tailed deer can be infected by and transmit SARS-CoV-2 to other deer through nasal secretions and fecal matter, researchers reported in the Journal of Virology. Fawns in the small study did not develop clinical signs of illness, but the virus replicated and was shed, suggesting cervids are potential viral reservoirs. Since captive mink are highly susceptible to this virus and have been infected by caretakers -- and, in turn, have infected other workers -- there is also concern that infected deer could pass this virus to wild mink and other wildlife.
Deer farmers must therefore take precautions to stop infected staff from passing COVID-19 on to deer. Many zoos are now taking such precautions. Unlike the influenza virus and other primarily airborne infections, this rapidly mutating coronavirus is capable of infecting many different species that could become reservoirs for future pandemics in the human population.
As for CWD control, the white-tailed deer population needs to be significantly reduced in most states. Encouraging wolf numbers, by prohibiting trapping, snaring and shooting them, would be prudent. Livestock keepers practicing nonlethal methods of wolf deterrence, such as the use of guard dogs, should be compensated for any confirmed losses of livestock to wolves (and not to disease, exposure or neglect).
These are the kinds of One Health issues that state and federal animal and public health agencies are beginning to acknowledge, questioning commercial farming practices in the bargain.
DROUGHT AND DISEASE IN DEER
Bluetongue and epizootic hemorrhagic disease are spreading among deer in the Northwest as dry conditions encourage animals to congregate near small, muddy water sources where the insects that spread these diseases proliferate. The viruses do not affect people, but the Washington Department of Fish and Wildlife advises deer hunters to avoid killing animals that appear ill. (Full story: Northwest News Network, Sept. 8)
These diseases are transmissible from deer to cattle and sheep. Ranchers would be better advised, in my opinion, to address the high deer population and various diseases putting their livestock at risk than continuing to advocate for the extermination of wolves and other predators.
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