Deadly Deer Disease Spreads In Texas, With No Easy Explanation

State officials are mystified as to how an aggressively contagious disease got into a state facility previously thought to be impenetrable.

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 country’s 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.

It also might have been a false positive. Follow-up tests failed to confirm the deer’s infection.

But environmental samples taken through the summer showed diseased prions lurking in feed and water troughs. When wildlife officials live-tested every deer in the herd in October, they turned up another positive. On Nov. 20, they killed all of the roughly 90 deer in the herd, depopulating the Texas Parks and Wildlife Department’s only deer research facility.