Concern on deer disease

The injection of tissue from leg muscles of deer infected with chronic wasting disease is enough to make susceptible mice sick with the same lethal condition. The finding is evidence that deer muscle harbors this infectious prion protein and that muscle alone can trigger the wasting disease. "We don't know how the infectious prion goes from the central nervous system into the muscle," said Glenn C. Telling of the University of Kentucky, lead investigator of the study that appears in the journal Science. "But it raises the possibility that hunters could be exposed to prions by consuming or handling meat." The infectious prion protein that causes chronic wasting disease in deer and elk has spread across the country, and last year was identified in upstate New York. The scientists say that the finding should be a wake-up call to humans consuming or handling venison. Chronic wasting is not unlike another infectious prion disease that crossed from cows into humans from contaminated beef. Mad cow or bovine spongiform encephalopathy, BSE, triggered a lethal disease called variant-Creutzfeldt Jakob disease, which has killed 170 people in the United Kingdom and elsewhere. Telling was concerned with growing evidence that animals incubating chronic wasting disease could expose humans to infection through muscle tissue. Using an animal model that carries the gene for the normal prion protein found in deer, they inoculated the mice with tissue from the brains of sick deer. The mice developed chronic wasting disease. This time, Telling and his team wanted to know whether muscle tissue would also trigger a lethal infection. They repeated the same experiment, but injected skeletal muscle instead of brain tissue. The muscle from these deer also harbored infectious prions, and the mice, once again, became sick. "I am not surprised" that the infectious agent is turning up in muscle, said Dr. Paul Brown, a Creutzfeldt Jakob expert. Scientists have not found high levels of infectious protein in the skeletal muscle of sick cows. That it was found in deer muscle is worrisome, Telling said. These diseases have a long incubation period, and if chronic wasting did jump species into humans there is no telling how that disease would present itself, he said. "There is no evidence of CWD transmission to human hunters," CDC medical epidemiologist Dr. Ermias Belay said. "But studies are limited."....