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Abstracts & Commentary
Synopsis: The emergence of chronic wasting disease, a transmissible spongiform encephalopathy in North American cervids, raises concern about potential transmission to humans, as has occurred elsewhere with bovine spongiform encephalopathy and vCJD.
Sources: Wisconsin deaths may be first instance of mad deer’ disease transmission to humans. Reuters Medical News. July 31, 2002; Regalado A. Spreading mad deer’ plague leaves US scientists baffled. The New York Times. May 2002; www.maddeer.org/plague.html; www.madison.com/captimes/opinion/column/guest/23628.php; McCombie B. Who is to blame for mad deer? The Progressive. August 2002; www.progressive.org/August%202002/mcco0802.html; Mad deer disease spreads across the USA—Hunters are starting to worry. Outdoor Life. Oct 1999; www.organicconsumers.org/Meat/maddeerusa.cfm; McCombie B. Stop the madness. Malady threatens Wisconsin’s elk, deer and, ultimately, people. Isthmus Newspaper. Madison, WI, July 2000.
Three deer hunters, aged 30 and younger from Utah, Oklahoma, and Maine died of Creutzfeldt-Jakob disease (CJD) during the period of 1997-2000. This raised an alarm since the national occurrence of CJD is approximately 1 per million, and the disease generally affects older people. Because of the common variable of consuming deer meat, autopsies were performed to confirm the diagnoses. The results of the autopsies demonstrated that the 3 had died of sporadic CJD and not the more "virulent" form of variant CJD (vCJD). More recently, the Centers for Disease Control and Prevention (CDC) is helping the Wisconsin health department review the cases of 3 hunting partners who died in the 1990s (2 in 1993 and 1 in 1999) of rare brain disorders.
vCJD, also known as "mad cow disease," is responsible for somewhere between 43 and more than 100 deaths in Europe; numbers vary depending on the source of information that is reviewed. Concern over vCJD is that it has a shorter incubation period and affects people at an earlier age.
Chronic wasting disease (CWD) is a variant of the mad cow disease that has been reported in deer and elk. CJD and CWD are classified as transmissible spongiform encephalopathy (TSE). The "infectious" agent associated with TSE is a small, relatively stable protein known as a prion. Prions are normally folded in a loopy pattern resembling a corkscrew, but when they unfold, they can cause other prions to change shape. This triggers the chain reaction that ultimately results in destruction of tissue, typically in the brain.
CWD was first noticed in a Colorado research facility in 1967 and slowly spread among wild deer and elk in Nebraska and Wyoming. It has also been found in captive elk in Colorado, Kansas, Montana, Nebraska, Oklahoma, Saskatchewan, and South Dakota. In Colorado at least 15% of some wild herds are affected. Because it has also been found in animals imported into Wisconsin, authorities there recommend following the lead of Montana, which placed a moratorium on the importation of all game farm animals. Testing of animals in Wisconsin was negative in 1999, but in 2001, 3 animals tested positive for CWD.
The Food and Drug Administration (FDA) has gone on record saying that mad deer disease is not a threat in the United States. Dr. Ermias Belay of the CDC told a panel investigating this that the cases "suggest a possible relationship with CWD," but investigations found "no strong evidence of a causal link" with the patients’ illnesses. The FDA has now suggested, however, that significant efforts be undertaken to remove the CWD from the US deer and elk populations.
Comment by Thomas G. Schleis, MS, RPh
Tom Thorn, a Wyoming state veterinarian, when discussing CWD, stated, "You cannot say with 100 percent certainty that it won’t transmit to people, but there is no evidence that it will transmit to people." That essentially sums up the wealth of knowledge we have about mad deer disease—maybe it’s a threat, maybe it’s not.
The list of TSEs is becoming extensive. We have scrapie in sheep, mad cow, mad deer, mad elk, CWD, CJD, and vCJD.
Having grown up in Wisconsin where the 4 favorite pastimes are eating, drinking, watching television, and hunting, I can only imagine the effect this information has had in that state. Wisconsin has approximately 100 deer and elk farms, and it is big business, with elk calves selling for around $1500 and bull breeding garnering as much as $20,000. Farms sell venison, and the velvet that peels from new elk antlers are considered an aphrodisiac in Asia, selling for $17 an ounce. Hunting guides can also package tours that cost from $1000 to $10,000 depending on the ultimate "prize." This is a billion-dollar industry with hunters killing close to half a million deer annually. With no mandatory reporting required for animals suspected of CWD, the disease could go unchecked for years.
What is important here is that this phenomenon be thoroughly investigated. Lab studies have suggested that CWD could theoretically infect humans by converting human prion proteins into their deadly form in a lab dish after exposure to CWD prions. If we have learned anything from mad cow disease, it is that denial can be deadly. With mad cow disease, it was years before British officials were convinced that there was a causal link and appropriate action was taken. It is vital that we do not allow the same mistake to happen here.