April, 27 2002 St. Louis Post-Dispatch by Tim RenkenIf you need something to worry about when you can't sleep at night, worry about Chronic Wasting Disease, CWD.
There in the darkness as you listen to the clock ticking you can envision deer and elk dying by the millions throughout the country from this strange, infectious disease. Then, in your churning imagination, it spreads to sheep and cattle. Then people. That sounds like bad fiction and probably is. But CWD doesn't disappear come daylight. It is real and it is infecting deer and elk in an increasing number of places. So far, it has been found in seven states and two Canadian provinces. The latest discovery, and for Midwesterners the most shocking, was in south-central Wisconsin this spring.
CWD is scary because scientists know so little about it. They don't know what causes it or how it is spread. They don't know how to prevent or cure it. They don't even know how to diagnose it except via post-mortem.
It isn't caused by a virus or bacteria but seems to be caused by a protein that by traditional definition isn't even alive. CWD damages the brain and inevitably progresses to the point that the victim can't function.
That's just like mad cow disease, to which CWD is related. So far, scientists haven't documented any spread of the disease from deer or elk to livestock. And people aren't thought to be at risk, but nobody knows for sure [There is evidence that CWD prions can infect human brain tissue--BSE coordinator]. The rare Cruetzfeldt-Jakob disease in humans is similar to CWD.
The disease isn't new to epidemiologists. It has existed in a relatively few wild deer and elk in a border area of Colorado and southeastern Wyoming for at least 30 years. It affected less than 6 percent of the mule deer in that area then and didn't spread.
Then elk ranching grew in popularity, with elk ranchers shipping pen-raised elk around the country. That's how CWD got out of the high plains and how the genie got out of the bottle.
For a while, CWD was found to have spread only among ranch elk here and there in the U.S. and Canada. And then, this spring, it showed up in wild white-tailed deer in south-central Wisconsin. Nobody knows how CWD got there, maybe from an elk ranch, maybe from the discarded remains of a deer or elk bagged out west. It's unlikely that an infected deer walked 600 miles from eastern Wyoming. So far, 14 of 516 deer killed by landowners and sharpshooter teams in a big area south of Madison, Wis., have tested positive.
That discovery stunned Wisconsin and sent a chill around the country. If CWD is in Wisconsin, it could be here or anywhere. It didn't show up in deer tested after hunting seasons in Missouri or Illinois last fall. Testing, of course, will continue.
States throughout the country are effectively banning the importation of deer and elk, trying to thwart the spread.
Scientists think CWD is spread via animal-to-animal contact, but they also have seen that elk placed in areas where infected elk had lived previously become infected. Even when that infected area was sterilized with powerful disinfectants, the elk placed there became infected.
To me, here's what is fearsome about this situation: For decades CWD remained confined in a small area of northeastern Colorado and southwestern Nebraska and even there the number of deer infected was low, less than 6 percent.
Why weren't more deer infected there? Probably because the deer population there is low and the deer widely scattered. Why didn't it spread elsewhere? Because deer and elk don't travel very far and that is big country.
When the disease was spread around by elk shipments, though, it got into populations that are large and dense.
Wisconsin's infected deer came from an area, around Mt. Horeb, that has lots of deer, 100 or more per square mile. Infectious diseases spread more rapidly where potential victims are concentrated. From early on, CWD spread quite readily among elk and deer confined in laboratories in Wyoming and Colorado.
A few places in the Midwest and East have deer populations as unnaturally dense as those around Mt. Horeb, Wis. Heaven forbid, but CWD could show up next in Town And Country.