Brucellosis investigation nears completion |

Brucellosis investigation nears completion

The Montana Department of Livestock (MDOL) announced July 17 that it has completed testing on all of the high risk cattle, and on a majority of all cattle, associated with a brucellosis-positive cow found in late May.

“We’ve completed testing on most of the cattle that had contact, or could have had contact, with the infected heifer, and everything came back clean,” said Dr. Martin Zaluski, State Veterinarian. “The investigation is not complete, as we are in the process of testing a few low risk animals, but we’re encouraged with the progress and results.”

A total of 1,061 cattle have been tested, including 776 from adjacent herds, 262 from source herds, and 23 trace-outs.

As mandated by federal regulation, investigators went back two years on animals that left the herd, animals that entered the herd, and contacts.

The origin of the infection has not yet been established, but the most likely source is either cattle or elk. Some elk in the Greater Yellowstone Area are infected with brucellosis.

“All of the testing so far has focused on ruling out cattle as the potential source,” Zaluski said. “As testing eliminates cattle sources, the likelihood that the infected cow contracted the disease from elk increases.”

Results that could help determine where the disease originated from are due before the end of the month.

Zaluski said the infected heifer – which was under a herd management plan – never got a chance to spread the disease, as she never calved.

The herd where the infected cow was found has been appraised and indemnity discussions are currently underway. Herds adjacent to the herd where the infected cow was found have been released from quarantine, and are now under herd management plans that include follow-up assurance testing.

“Producers have been extremely cooperative with the investigation,” Zaluski said.

The case was the second found in Montana within the last 12 months, and as such, it is expected that USDA will revoke Montana’s Brucellosis Class Free status. Montana had been brucellosis free since 1985.

The disease was discovered in a Bridger cattle herd in May of 2007, and was ultimately traced to a herd in Emigrant, located just north of Yellowstone National Park.

Brucellosis is a bacterial disease that causes pregnant cows to abort, and also causes decreased milk production, weight loss, infertility and lameness. A zoonotic disease, it can be passed through birthing fluids to humans in the form of undulant fever.

The USDA initiated an eradication program for the disease in the 1930s. While successful in eliminating the disease from cattle, the disease persists in elk and bison in and around Yellowstone National Park.

Brucellosis Class-Free status is achieved when a state fulfills all requirements of the brucellosis program and finds no cases of brucellosis in cattle and domestic bison herds for 12 months. When brucellosis is found in more than one herd of cattle in a brucellosis-free state within a two-year period, the state is downgraded to Class A status.


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