Early last year, a deer euthanized as part of a study at the Kerr Wildlife Management Area research facility in Texas tested positive for chronic wasting disease the deer equivalent of the brain disorder called mad cow in cattle and Creutzfeldt-Jakob disease in humans.

It was an alarming find for state wildlife officials, who have spent the last three years struggling to contain a recurring outbreak of the disease. Wildlife biologists widely view the highly contagious illness as the single greatest threat to the long-term health of the countrys cervids, a family of animals that includes deer, elk, moose and caribou. CWD causes brain proteins called prions to misfold, leading to a prolonged death by neurodegeneration.

The disease is present in free-ranging cervids in at least 32 states , according to the U.S. Geological Survey.