Each fall, millions of hunters across North America make their way into forests and grasslands to kill deer. Over the winter, people chow down on the venison steaks, sausage, and burgers made from the animals. These hunters, however, are not just on the front lines of an American tradition. Infectious disease researchers say they are also on the front lines of what could be a serious threat to public health: chronic wasting disease. The neurological disease, which is contagious, rapidly spreading, and always fatal, is caused by misfolded proteins called prions. It currently is known to infect …