Bovine tuberculosis in on a slight rise within the core infection area in the northeastern Lower Peninsula.

A report to the Natural Resources Commission last week showed that the incidence of deer testing positive for TB rose from 1.4 percent to 1.8 percent in 2007 for deer taken in Deer Management Unit 452. The DMU includes Montmorency, Alpena, Oscoda and Alcona counties.

Since first detected in an Alpena deer in 1975, bovine TB has been confirmed in more than 600 wild deer, most within that four-county area.

A doe shot in Bennington Township in Shiawassee County in December 2007 was the farthest south the disease has been detected in Michigan's wild deer herd.

Overall, the DNR tested 16,260 deer for TB in 2008. Of those, 36 tested positive, with 34 of them coming from the four-county area. The other two were taken in Presque Isle and Iosco counties.

DNR wildlife veterinarian Steve Schmitt said the long-term incidence rate is still declining, but the trend has been changing only slightly each year for the past six years. That may indicate the rate of infection has leveled off.

"We have brought the prevalence of TB down from 1995, but it appears to be stabilizing at this level during recent years," Schmitt said in a press release this week. "We may have lowered it as far as we can with our current strategy."

Michigan is one of the few places in North America where bovine TB has become established in the wild-deer population. Overpopulation and deer baiting practices are key factors in its spread.

State authorities have been working to contain the outbreak since the late 1990s, when the disease hit a high of 4.9 percent in 1995. Bovine TB rates have been dropping ever since, thanks in large part to efforts to reduce deer herd size and restrict bait piles.

The bait and feed ban was extended indefinitely in 2008 to include the entire Lower Peninsula after an incident of chronic wasting disease found in a privately owned deer herd in Kent County in August.

The owners of that Kent County facility were recently arraigned on felony charges for violating the ban on moving quarantined animals. The suspects were allegedly planning to release a buck from their quarantined facility into the wild. The buck tested negative for the disease.