Bovine tuberculosis testing, quarantine continue at Dane County dairy farm
A Dane County dairy herd at Maier Farms remains under quarantine since October 2018 when the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) confirmed Wisconsin's first bovine tuberculosis (bTB) case at the farm in more than 20 years.
The animal health incident began in late September 2018 when a cow at slaughter had lesions in its lungs consistent with TB.
The herd continues to be the only TB-affected herd in Wisconsin and is following a test and remove protocol to eradicate the disease, according to DATCP. The TB-affected herd and all locations where animals from the dairy are reared are under quarantine and animals can only move directly to slaughter, rendering, or a restricted feedlot.
DATCP, in collaboration with U.S. Department of Agriculture’s Animal and Plant Health Inspection Service-Veterinary Services (USDA APHIS VS), will continue testing the herd approximately every other month into the year 2020, and the herd will remain under quarantine until testing protocols are completed that show the disease is eliminated from the herd. Once the quarantine is removed, DATCP will test the herd annually for five years to assure there is no disease recurrence.
Trace investigations progress
DATCP’s Division of Animal Health and USDA’s APHIS VS staff continue to conduct trace investigations of sales from the affected herd. Since the confirmation of a TB-affected herd, there have been several hundred traces located in Wisconsin and 15 other states.
Currently 26 Wisconsin premises have some type of animal movement restriction due to exposure from the affected farm, according to DATCP. The investigations identify animals that were in contact with the TB-affected herd — any feeder animals are limited to move to slaughter and breeding animals must be tested.
Bovine TB in other states
Producers and veterinarians are most familiar with bTB from testing animals to meet import requirements into other states or from hearing about the challenges to control bTB in other states. Although most states hold an accredited TB-free status, state status does not prevent disease from entering a state.
Bovine tuberculosis is introduced into cattle herds by addition of or exposure to animals, wildlife, or people that are infected and shedding Mycobacterium bovis, the bacteria that causes bTB.
The strain of bovine TB in the cows matched a strain found in a Maier Farms worker in 2015, indicating the worker may have infected the herd.
DATCP recommends that producers work with their herd veterinarian to discuss on-farm biosecurity and practices to minimize risks of disease introduction.
Several other states with bTB-infected herds are conducting similar trace investigations, DATCP reported.
On March 18, Drovers reported Texas animal health officials confirmed a case of bTB at a large calf grower of over 70,000 animals located in the Panhandle region of the state.
Trace investigations for animals from or commingled with animals from the Texas infected herd have extended into a dozen states and will continue to expand as the investigation continues.
Prevalence of bTB in cattle herds in the U.S. is extremely low due to the National Tuberculosis Eradication Program. However, newly infected herds are identified annually as changes in dairy practices in the past 100 years have created new opportunities for disease introduction and spread within a herd.
Bovine TB is a zoonotic disease, meaning animals can infect people but people may also be a source of infection to cattle herds. The disease is most commonly transmitted through respiratory secretions and following close contact with infected animals that are shedding the bacteria. Infection may also be transmitted through unpasteurized milk of infected animals.
DATCP will continue testing and investigating traces from the Dane County herd. Producers are encouraged to learn more about bTB and work with their veterinarian to assess disease risks and develop plans to reduce the risks of disease introduction into their herd.
More information about the bTB investigation and resources are available at https://datcp.wi.gov/Pages/Programs_Services/TBInvestigation.aspx.