State deer herd managers were pleasantly surprised that the spread of the always fatal chronic wasting disease apparently slowed during the past year.
The Department of Natural Resources has recorded 10 positive samples, down from 12 the preceding year.
“It’s a good sign that the number of cases did not increase exponentially this year,” said Terry Haindfield, the DNR wildlife biologist coordinating disease control efforts.
That seemed likely, he said, based on the upward trend of positive tests since the first case was discovered in 2013. Iowa’s initial positive test was followed by three more in 2014, two in 2015 and 12 in 2016 — all in the northeast Iowa counties of Allamakee and Clayton.
That good news was countered by a CWD confirmation in south-central Iowa — the first hunter-harvested wild deer outside of northeast Iowa to test positive for the disease.
Haindfield said the doe was shot Dec. 5 in Wayne County, about five miles from the Iowa-Missouri border and about 50 miles from the closest confirmed case in Missouri.
The DNR will host a meeting next month with local hunters and landowners to form a plan to limit the spread of the disease in that area, he said.
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Since February 2015, the DNR, with the help of local hunters and landowners, has conducted three special efforts to collect additional samples, outside regular hunting seasons, from focus zones in Allamakee and Clayton counties.
The most recent effort, from Jan. 20 to 28, yielded 110 valid samples from Allamakee County and 90 valid samples from Clayton County. Those samples included two positive tests, both in Allamakee County, Haindfield said.
Those special collections provide additional information on the extent of the disease while removing some contagious animals from the herd, thus making it more difficult for the highly communicable disease to spread from one deer to another. That typically occurs through nose-to-nose contact or exposure to infected urine, feces and saliva.
CWD belongs to the family of diseases known as transmissible spongiform encephalopathies or prion diseases. It attacks the brains of infected deer or elk, causing them to lose weight, behave abnormally, lose bodily functions and die.
Since 2002 the DNR has tested more than 65,000 deer for the disease, with sample collection most intense in portions of northeast and Eastern Iowa bordering Wisconsin and Illinois, where the disease is much more prevalent, and in south-central Iowa near Missouri, where the disease has been detected.
So far chronic wasting disease does not appear to have affected the success of Iowa hunters.
Hunters in 2017-18 reported harvesting 105,544 deer in Iowa — an increase of more than 4,100 deer from the preceding season.