Origin of S. Dakota TB unknown | TSLN.com

Origin of S. Dakota TB unknown

The strain of bovine Tuberculosis (TB) present in a Harding County, South Dakota, herd appears to be nearly identical to a strain known to exist in the central region of Mexico, said the South Dakota Veterinarian Dr. Dustin Oedekoven in a news release.

It is not yet known how the Harding County herd contracted TB. It may never be known, said Oedekoven. A total of 41 infected animals were discovered within the affected herd.

According to Lyndsey Cole, USDA APHIS Public Affairs Assistant Director, producers receive indemnity payments if it is determined that their cattle must be depopulated to stop the spread of disease. "The amount of the indemnity payment equals the fair market value of the cattle, and that is determined through an appraisal before the animals are depopulated," she said.

The herd owners learned that some of their cattle were infected when three slaughter cows originating there were discovered by meat inspectors to be infected with TB. The cows had been fed in Nebraska and South Dakota and were slaughtered in Nebraska in February.

Nine herds are currently quarantined, including the affected herd and eight adjacent herds.

Dr. Oedokoven said four herds have already been taken out of quarantine. Some animals from neighboring herds have been euthanized for lab testing after testing positive in standard live tests.

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The herds neighboring the affected herd will be released from quarantine when their cattle all test negative.

Any cattle that are fence line neighbors to the affected herd must be tested. When an owner's entire herd tests negative, the herd will be taken out of quarantine. If a rancher owns cattle not adjacent to the herd that is a fenceline neighbor of the affected herd, the additional non-neighboring cattle do not need to be tested at this time.

False positive tests are not uncommon with the live tests, said Dr. Oedeoven, and lab testing of tissue following euthanization is the only way to determine for sure if the TB bacteria is present.

The bacteria can be further tested in an attempt to identify its origin, as in this case.

Harding County rancher Susan Nelson who, along with husband Wayne, owns the affected herd, said they are now waiting to hear from the state veterinarian to learn what they will be required to do next.

USDA has the authority to instruct the Nelsons regarding their management of the disease. It is possible that the agency would require whole herd disposition but at this time it is not known what it will implement.

"We've played every possible scenario in our minds but it doesn't do any good," said Nelson. "We just have to wait and see."

While they wait to learn the fate of their family cow herd, the Nelsons are calving heifers and providing labor to the neighbors who are carrying out mandatory testing.

As of March 21, 5,852 head of cattle – including the affected herd and some neighboring herds – in South Dakota were tested since the affected herd was identified.

Prioritization of testing and disposition of animals in these herds is based on risk assessment and in accordance with state and federal animal health regulations. Herd owners with concern regarding potentially exposed animals are encouraged to contact their local veterinarian or the state veterinarian's office. Caution is advised in commingling

new additions into established herds if there is a concern that some animals may be involved in the ongoing investigation, said Oedekoven in a news release.

Even with this positive herd, South Dakota continues to be considered a TB–free state.

"The US has nearly eliminated bovine TB due to a cooperative eradication campaign. South Dakota has officially been recognized as free of the disease since 1982. There is no immediate effect to our state status. The last affected herd in South Dakota was identified in Hutchinson County in November 2011. Thorough investigation of this outbreak will help us maintain our free status with USDA," he said. The status is important because South Dakota sends a lot of cows and calves out of state for feeding, said Oedekoven in an earlier TSLN story.

In some cases, the entire herd isn't being tested right away. Heifers might be tested first in order to complete the process before they start to calve, for example.

For more information, see TSLN's two earlier stories on this topic.

Eleven trace out states:

North Dakota

Montana

Wyoming

Colorado

Nebraska

Kansas

Oklahoma

Minnesota

Iowa

Missouri

Arkansas

There are thirty trace-out herds in South Dakota. Their locations are not public knowledge.

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