You asked if reindeer are susceptible to Chronic Wasting Disease.

SUMMARY

Researchers believe reindeer would be susceptible to Chronic Wasting Disease because of their genetic similarity to deer that contract the disease, but there is not yet a definitive answer to the question. The Canadian government is conducting experiments to determine if caribou, a member of the same species as reindeer, are susceptible to the disease, but does not expect to learn the results for several years.

CHRONIC WASTING DISEASE

Chronic Wasting Disease (CWD) is a rare, fatal disease found in members of the deer family (Cervidae). It attacks the brains of infected animals, causing them to become emaciated and behave abnormally before dying. CWD is one of a group of diseases known as transmissible spongiform encephalopathies (TSE's), which also include bovine spongiform encephalopathy (Mad Cow disease) in cattle, and Creutzfeldt-Jakob disease in people.

According to a 2004 report by a panel of Canadian scientific experts, (http://wildlife1.usask.ca/Publications/CWD%20Expert%20Report%20Final%20-%2020040804.pdf), CWD “is arguably the most important issue in the management of free-living cervids (members of the deer family) in North America. The disease has the potential to reduce cervid population in the long-term, and to create major socio-economic impacts.”

“Once established in a population of free-living cervids,” the report continues, “control or eradication of CWD is extremely difficult.”

State fish and wildlife agencies have taken steps to prevent CWD from infecting their free-ranging and farm-raised deer populations. Connecticut is one of a number of states that have banned the importation of captive members of the Cervidae family (Conn. Agency Regs. § 22-278-6). State regulations also prohibit the importation of deer, moose, and elk carcasses or parts from states or provinces where CWD has been confirmed (Conn. Agency Regs. § 26-55-4).

Scientists do not know how long CWD has been present in North America. It was first detected in captive deer in Colorado and Wyoming about 40 years ago, and in wild deer in 1981. According to the Centers for Disease Control (CDC), by 2007 CWD had been found in two Canadian provinces and 11 states, including Illinois, New York, West Virginia, and Wisconsin. (There is no evidence to date that CWD has been transmitted to humans, although the CDC states that more research is needed.)

Researchers say CWD occurs naturally in mule deer, white-tailed deer, and elk, which are members of the deer family, as are moose, reindeer, and caribou. Reindeer and caribou belong to the same species, Rangifer tarandus. No cases of CWD in reindeer or caribou have been reported.

Although CWD behaves in most respects as an infectious disease, scientists do not know exactly how it is spread. “TSE's are entirely new to science,” the Canadian report stated, “and thus every aspect of CWD is shrouded in uncertainty.”

Transmission can apparently occur among susceptible cervid species, or from infected animals to the environment, and then to susceptible animals. Animals may be infected for a long time before showing symptoms. White-tailed deer and mule deer (although not elk) can now be tested for CWD with tonsil biopsies (http://www.cfsph.iastate.edu/Factsheets/pdfs/chronic_wasting_disease.pdf), although this method has not been approved by the U.S. Department of Agriculture.

TSE's are thought to be caused by an abnormal form of protein-like infectious particles called prions. The abnormal prion infects the host by promoting the conversion of normal cellular proteins into the abnormal

form. Researchers believe that the likelihood of transmission of CWD between deer species depends on the similarity of the infective prion protein to that of the host prion protein.

Researchers raise the idea of a “species barrier” that must be overcome before an infective prion strain from one species causes the disease in another species. But the Canadian panel stated that “it can be concluded that the species barrier may not completely protect other cervid species, including caribou and moose, from CWD.”

“Although no natural cases of CWD-affected caribou or moose have been reported,” the report stated, “CWD recently has been induced experimentally in moose…Susceptibility of caribou to CWD remains unknown, but some level of susceptibility seems likely based on the similarities between the normal cellular prion protein of caribou and the normal cellular prion protein of mule deer.”

Similarly, the authors of a 2007 article in the Journal of Wildlife Diseases report that “caribou prion alleles are identical or nearly so to those of wapiti (North American elk), white-tailed deer, and mule deer…Genetics seems to permit the spread of chronic wasting disease from middle-latitude deer to high latitude caribou in North America," ("Prion Protein Genes in Caribou From Alaska,” Journal of Wildlife Diseases, 43 (2) 2007, http://www.jwildlifedis.org/cgi/reprint/43/2/224.pdf.

We also spoke with Bryan Richards, CWD Project Leader for the U.S. Geological Survey's National Wildlife Health Center. He, too, states that “at least on a genetic basis, there's no scientific reason why reindeer would not be susceptible to CWD.” According to Richards, the Canadian Food Inspection Agency is now conducting CWD experiments with caribou, but those test results will not be known for several years.

PF:ak