Wildlife agencies dealing with chronic wasting disease often lament that it’s hard to convince hunters that CWD is quietly killing deer that would otherwise be available to them. Unlike “blue tongue” diseases like epizootic hemorrhagic disease, which kill deer by the scores, deer killed by CWD typically die alone and out of sight.

CWD sufferers often move toward water to slake their thirst and fevers, but struggle to drink. They often dunk their entire head into rivers or ponds because they struggle to slurp water like healthy deer.

Even so, wildlife biologists in areas with CWD often see the disease in its advanced stages. From 2009 through late 2013, for example, biologists responded to 91 reports of sickly deer in Iowa, Dane and Sauk counties near Madison, Wisconsin. They shot each deer or gave the landowner permission to shoot it, and then tested it for CWD.

About half the deer had CWD. Specifically, 42 had the always-fatal disease, while the others had been hit by cars or suffered from lung infections or cranial abscess disease.

“Clinically sick” deer in winter often show up alongside homes and garages, which provide refuge from wind and predators, assuming no dog lives there. In one case, a CWD-infected deer spent two days inside an elderly woman’s open garage, fouling its interior with drool and feces. More common are diseased deer lying against south-facing house or garage walls to catch the sun’s warmth.

Other homeowners report deer bedded beside the PVC exhaust outlet from their home’s furnace. They usually lie there until approached. If they get up and run, they only go about 20 or 30 yards before stopping.

In most cases, though, sick deer seek seclusion, and once they’re debilitated, they’re easy prey for coyotes. No matter how they die, they’re soon consumed by decay and scavengers, and no one knows CWD killed them.

For more information on chronic wasting disease in North America, visit the CWD Alliance’s website.