A heifer from a farm in northern Minnesota's Beltrami County has tested positive for bovine tuberculosis (TB), dealing a disappointing setback to the state's cattle industry, the Minnesota Board of Animal Health said Thursday.
The state has now detected bovine TB in eight beef herds in Roseau and Beltrami counties.
While the infections pose little risk to human health, the latest discovery slows the industry's effort to regain the crucial "TB-free" status, the board said.
The Beltrami County herd was quarantined last year after a TB investigation revealed the owner had bought animals from a TB-infected farm. The entire herd was tested at that time, and all animals tested negative.
But in a follow-up test this fall, two animals tested "suspect" for bovine TB. Tissue samples were submitted to the National Veterinary Services Laboratory in Ames, Iowa, and bovine TB was confirmed in a 12-month-old heifer Tuesday. The second animal was negative.
That herd numbered about 350.
The state's cattle herds will be declared free of TB only after two years pass without a positive test. Losing the "TB-free" label poses a cumbersome financial burden for ranchers, who must then pay for testing if they want to sell their animals outside of the state.
This latest discovery means the industry must start over toward having two years of being TB-free. It had been about a year into achieving that status before this positive test, said Board of Animal Health spokeswoman Malissa Fritz.
In addition to traces and area testing, the state is conducting TB testing in cattle herds statewide. This statewide surveillance began before discovery of this latest infected herd and is expected to be complete by the end of the year.
So far, the state has tested about 1,200 herds, and all have tested negative for bovine TB.
Paul Walsh 612-673-4482