Scientists at the University of Wisconsin have discovered that prions, which cause chronic wasting disease in deer, can live in the soil.

CWD is one of a family of neurological disorders known as transmissible spongiform encephalopathies that also include "mad cow" disease, sheep scrapie and Creutzfeldt-Jacob disease in humans. The diseases are incurable.

The researchers found that certain types of soil serve as prion repositories, and the prions found there can remain dangerous. Because animals sometimes consume soil to meet their mineral needs, they could become infected.