DuPage County Forest Preserve officials are expressing relief after follow-up testing showed the discovery of a deer with chronic wasting disease most likely was an isolated occurrence.
Officials were worried the disease, which is fatal to deer, had spread to DuPage after an infected animal was found in Mallard Lake Forest Preserve near Hanover Park. It was the first time a deer in DuPage has tested positive for the neurological disorder.
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But the Illinois Department of Natural Resources has informed the district that the results from 20 additional deer tested for chronic wasting have all come back negative. Those extra deer were culled from Mallard Lake and the nearby Hawk Hollow Forest Preserve.
"This would tend to indicate that it (the infected deer) was more of an anomaly," said John Oldenburg, director of the district's office of natural resources.
The forest preserve district has been doing annual testing for chronic wasting since 2002, the same year the disease first was detected in Illinois.
The infected animal was among 250 deer culled between November and mid-December as part of the district's annual deer removal program. Of the culled deer, 85 were tested for chronic wasting.
Oldenburg said it appears the infected deer came from another county.
"Deer do seasonal movement," he said, "and there are counties to the north that have this disease."
The state's first case of chronic wasting was reported in 2002 in Boone County. Since then, there have been 372 positive results found in 11 counties in northern Illinois, officials said.
District officials stress there's no evidence chronic wasting can be transmitted to humans. But while there's no threat to the public's health or safety, the disease is deadly for deer.
Chronic wasting is a progressive neurological disease that affects deer, elk and moose. It causes them to become emaciated, display abnormal behavior, lose coordination and eventually die. It's also highly transmissible between deer.
One of the goals of DuPage's deer management program is to help prevent the transmission of diseases.
"We thought that by managing so effectively we, hopefully, had very healthy deer at low numbers that were in balance with the ecosystem and maybe that (chronic wasting) wouldn't hit us," said Oldenburg.
Because of what happened, Oldenburg said the district likely will manage deer "a little bit more intensely" in the northern part of the county when culling resumes in November.
That would increase the sample size of deer being tested for chronic wasting and reduce the size of the deer population in that area.
"We definitely don't want this disease to get in," Oldenburg said, "because that would put deer at risk."