Montana Outdoors Magazine
How Prevalent is CWD?
Few things are simple about chronic wasting disease (CWD), the brain-eating illness slowly spreading among Montana’s deer herds. But there’s one simple math calculation that can indicate just how strong a hold CWD has on any given deer herd.
It’s called “prevalence.”
Prevalence is determined by dividing the total number of animals tested in a given area by the number of CWD-positive results. “It gives us a clear idea of what percent of a herd is infected,” says Dr. Emily Almberg, a wildlife disease ecologist with Montana Fish, Wildlife & Parks.
For instance, if FWP tests 100 deer from a hunting district and 15 are positive for CWD, the prevalence in that district is 15 percent.
