Chronic wasting disease spreads among deer, elk, moose; now found in 24 states and four other countries

Incidences of chronic wasting disease in North America (U.S. Geological Survey map)

Chronic wasting disease is continuing to spread rapidly among deer, moose and elk. "Last winter, Tennessee became the latest of 24 states to report CWD infections, which have also been found in two Canadian provinces, Norway, Finland and South Korea," Jason Bittel reports for The Washington Post. "Now, as it strikes animals across a widening territory, concern is growing among scientists and public health officials that the disease might leap to humans."

CWD is spread by prions, mutated proteins. Sounds familiar? Prions are also how mad-cow disease spreads. Since the 1990s, the human form of mad-cow, Creutzfeldt-Jakob disease, has killed more than 220 people worldwide. Prion diseases are fatal, with no known cure. "Some experts say that in a nation with an estimated 10 million deer hunters harvesting 6 million deer a year and eating many of them, it may be just a matter of time before chronic wasting makes its way to us," Bittel reports.

Michael Osterholm, the director of the Center for Infectious Disease Research and Policy at the University of Minnesota, estimates that as many as 15,000 CWD-positive carcasses may have been eaten last year, which he says ups the chances that the disease will eventually leap to humans. "There are thought to be eight strains of CWD, and every time one goes through an animal, Osterholm said, there’s a chance it might adapt in a way that allows it to pass into humans," Bittel reports.

A study last year found that macaque monkeys could catch CWD under certain conditions; that's alarming since macaques and humans have very similar DNA. In the meantime, scientists urge hunters to have their deer tested if it's harvested from an area where CWD has been found.