Bovine TB discovered in Arenac County
ARENAC COUNTY — A case of bovine tuberculosis (TB) was reported in Arenac County by the National Veterinary Services Laboratory Sept. 5, according to Northeast Michigan Extension dairy expert Phil Durst.
Durst said the TB was found in a dairy heifer in a herd of cattle that was being prepared for slaughter. He said currently, he does not know the farm or location within the county where the TB was discovered.
Because of the presence of TB, farms in the surrounding area can expect testing by the U.S. Department of Agriculture in the near future.
“They will do both circle testing and trace testing from this herd,” he said. “Circle testing is when they will draw a three-mile radius around this herd, and test any herd that falls within this area. Producers don’t have to know where the original herd is, because they will be contacted.”
Trace testing, Durst added, is when the herds the infected animal formerly belonged to are tested. Because this animal was being slaughtered, herds in its location history will be tested, he said. According to Durst, it is believed the infected heifer was also housed in Saginaw and Gratiot counties.
To illustrate the movement of the infected animal, Durst referred to the Saginaw County location as “herd A” and the Gratiot County location as “herd B.”
“It was likely infected in either herd A or herd B,” he said. “If it was infected in herd B, then we think that it could’ve got it from herd mates or raw milk fed to the calves. An investigation has not been done.”
He added that those familiar with the situation believe the heifer was infected before it was transported to Arenac County.
“That would probably be our working assumption, because we know herd B had infected animals in it,” he said.
Durst added that once a cow is identified as being infected with TB, its movements over the past five years are followed. That is how it was discovered that the Arenac County heifer was once a part of herds in Saginaw and Gratiot counties, he said.
With the discovery of the disease locally, Durst said the best-case scenario is that it was an isolated incident.
“The worst-case scenario is that they find other animals that are positive,” he said.
Although it is not known how the infected heifer contracted TB, Durst said the case of TB is a reminder that farmers need to protect their herds from coming into contact with wildlife, especially deer, which is how bovine TB is often contracted.
“Even herds in areas outside of the TB management area need to protect animals from wildlife,” he said.
Durst added the TB deer management area in Michigan is Oscoda, Alpena, Montmorency and Alcona counties.