Sept. 30 marks the first day of Ohio’s deer season, another in which chronic wasting disease casts a shadow on the hunting landscape.

Since being identified in the fall of 2014 among whitetail deer in a captive herd on a preserve in Holmes County, the fatal disease has not been found in Ohio deer, captive or wild. The Ohio Division of Wildlife monitors the place where the stricken deer lived and maintains rules and restrictions for hunting whitetails in the area.

Whether any future deer will die of CWD in Ohio can be debated with skepticism and not predicted with certainty.

Still, there’s little argument the disease caused by a misshaped, replicating protein known as a prion will linger in the infection area long enough to threaten deer for years, possibly decades. The staying power of the prion has been documented since CWD first attracted scientific attention.

Initially identified in mule deer in Colorado and Wyoming, the disease spread into Canada and the Midwest with deer exchanges among commercial captive operations.

The wake-up call came when CWD began claiming whitetails in Midwestern states including Wisconsin, Minnesota and Illinois. Outbreaks have occurred in Iowa, Arkansas, Michigan, New York, Maryland, West Virginia and Pennsylvania. The infected Ohio deer were linked to a captive herd in Pennsylvania.

The most troubling aspect of the CWD saga is twofold: The disease is incurable and seemingly unstoppable. The prions are dispersed into the environment by infected animals in many ways, including through urine, scat and body fluids, the transfer of which occurs during mating, gestation and birth. Prions in soil can be taken up by plants on which deer feed.

From the time a deer ingests the prion until symptoms occur is thought to be a minimum of 17 months. The maximum incubation period could be years, but that timespan is undetermined. Some genotypes in each vulnerable species are thought to be less susceptible to developing symptoms, though whether those genotypes confer immunity is unknown.

That means at this point every whitetail, mule deer, elk, moose, caribou and reindeer in North America is at risk. A few CWD-infected animals recently were identified in northern Europe, though no connection with the North American outbreak has been established.