Michigan animal-health officials have confirmed bovine tuberculosis in two cattle herds in Iosco County, and investigations into the source and possible spread of the disease are under way. The Michigan Department of Agriculture and Rural Development (MDARD) announced the detections on 15 September: one herd was found through a trace investigation linked to a previously confirmed TB-positive herd, the other through routine whole-herd surveillance testing.

"These latest detections of bovine TB underscore why this disease is so challenging to address and the critical need to thoroughly investigate animal movements and maintain active surveillance in order to manage this disease," said State Veterinarian Nora Wineland. MDARD, she said, will keep working with agency partners, producers and stakeholders to protect the state's cattle industry and animal and public health.

Bovine TB is a bacterial disease that can infect all mammals, including people. In Michigan it is established in free-ranging white-tailed deer in parts of the north-eastern Lower Peninsula, which creates a route of transmission between deer and cattle. The state has two zones: Alcona, Alpena, Montmorency and Oscoda counties form the Modified Accredited Zone, and the rest of Michigan is the Accredited Free Zone. Iosco County lies outside the four-county zone — but TB-infected wild deer have been found there before, and an infected cattle herd was confirmed there in May 2026.

Epidemiological investigations will determine whether further cases are connected to the newly identified herds, and whole-genome sequencing will be used to trace the source of the infections. Inside the Modified Accredited Zone, state and federal officials rely on routine cattle surveillance, mandatory animal identification, movement certificates and wildlife biosecurity programmes; officials also point to deer hunting in the north-eastern Lower Peninsula as part of managing the disease in the wild herd and reducing the risk to cattle and people.

Source: AGDAILY