Bovine tuberculosis investigation continues
North Dakota officials are working closely with the U.S. Department of Agriculture to investigate and test North Dakota cattle related to the confirmed bovine tuberculosis (TB) cases in Harding County, S.D.
Bovine tuberculosis was identified in three beef cows during routine slaughter inspection by U.S. Department of Agriculture Food Safety Inspection Service inspectors at two Nebraska slaughter plants in February 2017. The cows had been in feedlots in Nebraska and South Dakota since November 2016.
North Dakota State Veterinarian Dr. Susan Keller said the North Dakota Board of Animal Health are working to support the investigation. She said the appropriate movement restrictions are in place to protect the state’s livestock industry.
“It is important for anyone moving livestock to follow all import and export requirements of their state,” Keller said. “Producers should work with their veterinarians to get health certificates and to ensure they are following correct protocol.” Market records were used to identify the herd of origin, which was tested by state and federal animal health officials, revealing additional infected animals. 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 more than 8,000 head, were quarantined for testing. One herd has been released from quarantine with negative results of testing in all cattle 2 years of age and older. Testing is in progress in the remaining adjacent herds, and the majority of that work should be completed in coming weeks.
Keller said that the herd in question was quarantined and will be depopulated. A second adjacent herd exhibited a confirmed TB case in one cow and is under additional investigation.
The National Veterinary Services Laboratory in Ames, Iowa, 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. This strain is not related to the recent strain found in Canadian cattle or previous cases identified in South Dakota cattle or in Michigan wildlife and livestock. Additionally, it does not appear to be genetically similar to other strains that are sometimes found in the United States or in feeder or rodeo cattle of Mexican origin, nor is it similar to the bacteria identified in captive cervids (deer and elk). Rather, this case appears to represent the introduction of a new strain of Mycobacterium bovis into the United States. State and federal animal health officials working with the case will continue to investigate possible pathways of introduction into this herd.
Bovine TB is a chronic bacterial disease of cattle and can affect other species of mammals. Early infections of tuberculosis don’t often show clinical illness. Common symptoms are progressive weight loss, a low-grade fever, weakness and refusal of feed. The disease is transmitted through the air, by ingestion or through breaks in the skin.
For more information, contact Keller, Dr. Beth Carlson or Dr. Sara McReynolds at (701) 328-2655.