Update March 17, 2017 – Bovine Tuberculosis update from the South Dakota Animal Industry Board regarding the Harding County TB case.
• The herd remains quarantined and 41 infected animals have been removed from the herd. Final disposition of remaining animals in the herd is being determined.
• Thirteen adjacent herds, comprised of over 8,000 head, were quarantined for testing. One herd has been released from quarantine with negative results of testing in all cattle two years of age and older. Testing is in progress in the remaining adjacent herds and the majority of that work should be completed over the next 3 weeks.
• Cattle premises in 11 other states are also being investigated. Completion of the investigation can be expected to extend into the fall months of 2017.
• In response to the discovery of Bovine TB in Harding County, South Dakota Game, Fish and Parks is coordinating with the SD Animal Industry Board to sample area wildlife for the disease.
• The National Veterinary Services Laboratory (NVSL) in Ames, IA, has conducted whole genome analysis of the bacteria isolated from some of the affected animals from the Harding County herd. Experts have concluded that this strain of bacteria is nearly identical to a strain that is known to exist in dairy cattle in the Central region of Mexico and that it has not previously been identified in the United States.
• Rather, this case appears to represent the introduction of a new strain of Mycobacterium bovis into the United States
Harding County, South Dakota ranchers have been dealing with the discovery of bovine tuberculosis at the Wayne and Susan Nelson ranch. A meeting was held at the Buffalo, S.D. school gym on March 9 by South Dakota State Veterinarian Dustin Oedekoven to help walk area ranchers through the coming weeks and what it means to their cattle operations.
As of the meeting, 26 animals in the Nelson herd had been confirmed with TB and continuous testing would be taking place. Neighboring ranches, 13 total, have been quarantined and will also have cattle tested before any livestock can be sold. Approximately 8,000 head will undergo testing.
“It is rare to find adjacent herds that are infected, it could happen, but it is rare,” Oedekoven told the ranchers.
The quarantined ranches must pass two TB tests before being released from the quarantine.
Oedekoven also told the large audience that there was not enough information yet to point to a source of the TB. Several in the audience asked questions about the local deer population being the source. Oedekoven said the South Dakota Game Fish & Parks is aware of the discovery and has meetings planned to address surveying deer or other wildlife in the vicinity.
Trace out and source herds are also being investigated, and Montana has just announced two herds with ties to the main infected herd in South Dakota will undergo TB testing.
“Following up on interstate movements after a detection of TB or other animal disease is a routine part of disease investigations,” said Tahnee Szymanski, Montana Assistant State Veterinarian. “Our strong working relationship with South Dakota is critical in promptly identifying animal movements and protecting the state of Montana.”
TB is a very slow spreading disease with animals not showing visible illness. “It’s not like you can pick one out of the herd. Very rarely do we see a cow with clinical signs while in the herd,” Oedekoven said.
Since TB is a respiratory disease it is most commonly spread through nose-to-nose contact and inhalation. It primarily affects cattle, but can be transmitted to any warm-blooded animal, including people. Currently, there is no vaccine for the treatment or prevention of the disease.
The TB was discovered when three cows were processed in Nebraska slaughtering facilities in February. USDA inspectors there flagged the animals and contacted the South Dakota Animal Industry Board with their findings. From there the animals were traced back to Harding County. The infected animals never entered the food supply chain.
Oedekoven said his main goal as state vet is to ensure South Dakota maintains its TB-free status and everyone can continue to market cattle without restrictions.
In talking with Harding County ranchers March 9 it was evident no one is pointing blame. Instead, the ranching community (population 1200) is pulling together to get through the next several weeks of testing cattle. Everyone is hoping for the best for the Nelsons and the quarantined ranches.