Good reason why CWD spreads so fast
The recently discovered outbreak of chronic wasting disease in southcentral Pennsylvania wild deer clearly shows the insidious nature of the infection, and why it probably can’t be stopped
Three animals taken by hunters during the two-week firearms deer season last fall tested positive for the disease, according to the Game Commission.
One was an adult buck in Frankstown Township in Blair County; another was an adult doe in Freedom Township, also in Blair County. The third was a 11⁄2-year-old buck from South Woodbury Township in Bedford County.
Significantly, none reportedly seemed sick before they were taken.
The hunters who shot the deer said all appeared healthy when encountered, noted Brad Myers, director of the commission's southcentral region office. “They said there was no indication these deer had anything wrong with them,” Myers said at a recent press conference.
That scenario is disturbing – and discouraging. Because it is hard to imagine how CWD can be reined in here in the commonwealth. CWD has a long incubation period and typically takes at least 16 months for an infected animal to show signs of illness. And early on, infected animals may not test positive for the disease, either.
Deer and elk with CWD may not produce any visible symptoms of the disease for a number of years. And older animals, especially males, are most likely to be infected.
Eventually, as the disease progresses, animals may exhibit loss of weight, excessive salivation, trouble swallowing, difficulty in judging distance, and drooping ears. But by then, they likely have spread the disease to many other animals.
It is not certain how CWD is transmitted, but deer observation in Colorado and Wyoming – the so-called “endemic area” where the disease was first discovered in the 1970s – has shown that both lateral (animal to animal) and maternal (mother to offspring) transmission is possible.
That means once it becomes established in wild deer populations such as Pennsylvania’s, it stays for a long, long time. And now with an outbreak occurring at a game farm in Adams County and in wild deer in Blair and Bedford counties – more than 100 miles apart – it may be naïve to think it can be stamped out.
Somehow, after CWD was discovered in both farm deer and wild deer in southern New York in 2005, after many deer were killed and farms quarantined, the disease disappeared.
By comparison, the same year, CWD was found in a West Virginia deer. Dozens of deer there have since been detected with CWD and the outbreak has spread across the state.
I fear Pennsylvania is following the West Virginia CWD path, but honestly, at this point, who knows?