By Andi Anderson
A new bovine tuberculosis (M. bovis) case discovered in Michigan has raised concern across the state, as it was found outside the usual high‑risk area for the disease.
The infected cow was identified during routine testing by the USDA Food Safety and Inspection Service in February. A suspicious lymph node was examined, tested, and confirmed positive, and officials traced the animal back to a herd in Charlevoix County. This marked the first case ever identified in that county.
Further testing revealed additional infected animals, leading to a full herd quarantine. Dr. Nora Wineland, state veterinarian for the Michigan Department of Agriculture and Rural Development (MDARD), confirmed the findings.
She emphasized the seriousness of the situation, stating, “This latest detection of bovine TB highlights two important realities. How challenging the disease is to address;, and why it is so crucial to use all of our tools for detection to swiftly identify cases and take actions to limit disease spread.”
Michigan’s highest‑risk region for bovine tuberculosis is the Modified Accredited Zone (MAZ) in the northeastern Lower Peninsula. “The area of highest risk for bovine TB, and where most TB-infected cattle herds and wild deer have been identified, is in the Modified Accredited Zone (MAZ) of Michigan’s northeastern Lower Peninsula,” Wineland says. Charlevoix County is outside this zone, making the new detection particularly concerning.
This case follows a similar incident in November 2025 in Presque Isle County. Together, these represent the 84th and 85th bovine tuberculosis cases discovered in Michigan since 1998.
Bovine tuberculosis historically affected cattle nationwide in the early 20th century, leading to large-scale eradication programs involving testing, quarantines, and removal of infected animals.
While most states, including Michigan, achieved near‑eradication by 1979, wildlife reservoirs such as white‑tailed deer have kept the disease circulating in some regions.
Today, outbreaks require extensive surveillance of both livestock and wildlife. Wineland writes, “Controlling bovine TB and protecting Michigan’s cattle industry is a top priority for MDARD.” She explains that producers in high‑risk and surrounding areas must follow strict biosecurity rules to help maintain market access for cattle, meat, and milk products.
A confirmed case can significantly disrupt farm operations. Dr. James Sunstrum from the Wayne County Health Department explains that authorities “lock down that cattle producer for up to six months.” This prevents farms from selling milk or animals while the herd is retested and decisions about culling are made.
Sunstrum notes, “This is a major event for the cattle producer because it locks down his herd. So it’s very economically painful for this operation.”
Bovine tuberculosis can affect all mammals, including humans. People may become infected through close contact with sick cattle or by consuming raw, unpasteurized milk.
Sunstrum notes these cases are rare, stating that Michigan typically records only one or two human cases of bovine tuberculosis each year, usually linked to travel. He also emphasizes that pasteurization kills the bacteria that may enter the food supply, reinforcing why milk safety laws were created.
Despite public health warnings, some groups continue to promote raw milk consumption. Experts urge caution, reminding communities of the historical risks associated with unpasteurized dairy products.
Photo Credit: gettyimages-ahavelaar
Categories: Michigan, Livestock