The numbers are in, and to deer hunters they’re discouraging.
They show that chronic wasting disease is spreading inside West Virginia, and it’s infecting more deer in areas where it occurs. Jim Crum, deer project leader for the state Division of Natural Resources, called statistics from the agency’s latest CWD sampling effort “unsettling.”
“Of the 591 tissue samples we extracted from hunter-killed deer last fall in Hampshire County, 29 were positive for CWD,” Crum said. “That’s the highest number of positives we’ve ever had. The year before, by way of comparison, we took 672 samples and got 16 positives.”
The disease, which kills deer in much the same way mad cow disease kills cattle, was first discovered in the Mountain State near Slanesville, Hampshire County, in 2006. DNR officials immediately set up a “CWD containment zone” in an effort to keep the always-fatal malady from spreading.
They encouraged hunters to kill more deer by setting up a special antlerless-deer hunt within the county. They imposed restrictions on transporting deer carcasses outside the containment zone. They took tissue samples from hunter-killed deer at 11 game-checking stations within Hampshire County. They had agency sharpshooters kill additional deer each spring to help monitor the disease’s prevalence.
Despite their efforts, CWD continued to spread slowly but steadily.
Based on samples taken within a designated 39-square-mile area within the containment zone in central Hampshire County, the prevalence of infected deer has increased from 7 percent to almost 25 percent. Crum said he doesn’t know how high the percentage might eventually go.
“It probably won’t go to 100 percent,” he said. “The highest known prevalence ever reported was about 50 percent, so we’ll probably top out short of that.”
Equally disturbing to DNR officials has been the disease’s geographic spread. In 2006, all the CWD-positive samples were contained within a 15-square-mile area. Since then, the infected area has expanded to 108 square miles and has crossed the line into neighboring Hardy County.
Crum said the expansion has been steady.
“In 2006, the area was 15 square miles; in 2007, it was 25; in 2008, it was 32; in 2009, it was 49; in 2010, it was 61; in 2011, it was 73; in 2012, it was 85; and last year it was 108,” he said. “If you graph that out, it’s a pretty neat line.”
Following that trend, the infected area should increase by approximately 13 square miles a year, a rate that could encompass all of Hampshire County within 40 years.
The worry is that deer from the containment area — especially young, footloose bucks — might wander far enough outside the zone to expand it rapidly. CWD-infected whitetails have been found in parts of Maryland, Virginia and Pennsylvania not far from Hampshire County’s borders.
Crum said the current CWD-positive count for neighboring states’ wild-deer population stands at seven for Virginia, five for Pennsylvania and two for Maryland.
CWD was originally endemic only to states west of the Mississippi River, but leapfrogged its way fairly quickly to Midwestern, Mid-Atlantic and Northeastern states. Because several states’ “first cases” were found near captive deer facilities, wildlife disease experts suspect that deer farmers’ tendency to swap animals across state lines helped spread the disease more rapidly than it otherwise might have.
Crum, himself a Ph.D. in wildlife diseases, said biologists in nearby states are now fully alert to the disease’s potential for spread.
“When we first found CWD here, a few of us biologists from West Virginia, Virginia and Maryland started meeting informally to keep abreast of what was going on,” he said. “At our last meeting, which took place just recently, there were close to 40 people, including folks from Ohio, New York, Delaware and New Jersey.”
Crum said biologists doubt that CWD can be limited to existing areas, mainly because the U.S. Department of Agriculture’s effort to monitor the disease among captive herds “is broke.”
“They have a list, but not all the animals known to be infected are on the list, and [deer farmers and breeders] are transporting animals all over the place,” he said. “Right now, I’m not optimistic we can keep the disease from spreading.”