On Thursday, October 14, the Montana Department of Livestock held a public meeting in the Commercial Building at the Blaine County Fairgrounds. To a crowd of approximately 100 people, State Veterinarian, Dr. Marty Zaluski and Assistant State Veterinarian Dr. Tahnee Szymanski shared extensive information about bovine tuberculosis, the investigation to date, upcoming epidemiologically linked herd testing, and subsequent wildlife surveillance.

Calling the discovery "an event of significance," Zaluski confirmed that this is the first case of bovine tuberculosis (TB) in decades in Montana. Although it potentially compromises the state's TB free accredited status, Zaluski explained that if an affected herd is detected in a State or zone classified as accredited-free, and the herd is depopulated and an epidemiologic investigation completed within 90 days of the detection of the affected herd with no evidence of the spread of tuberculosis, the State or zone may retain its accredited-free status.

"Because this situation is of such importance and we're accountable to higher powers, we have a team of federal officials and trained staff here with us. The test cost responsibility and vet costs involved in this investigation will be covered by federal and state entities," Zaluski said.

The TB case was discovered during a routine inspection at a Minnesota meat processing plant. Lesions were found in a cow at slaughter and traced back to a beef herd in Blaine County. Because subsequent herd testing revealed that Mycobacterium bovis (M. bovis)-the bacteria that causes TB-exists, the herd was placed under quarantine.

When live animal testing found additional cases in the herd, this discovery triggered a full-scale investigation. "We are working closely with the herd owner, United States Department of Agriculture (USDA), tribal, and wildlife officials," Zaluski stated. "Because eradication of this disease is our goal, our efforts will now include the testing of adjacent herds and herds that have shipped animals into or received animals from the source herd. We're hoping to determine if other herds or wildlife are involved, and if possible, to determine the source of disease introduction."

According to Zaluski, given current information obtained through contact tracing, the buffalo herd on Fort Belknap Reservation is not considered at risk.

"In the nation, we see about 10-12 cases of TB in a year, with most of those cases coming from a white tail deer herd in Michigan. We also see cases in Mexican origin cattle. Others are novel strains, never seen before. This is one of those cases. At this time, the origin of the infection is not known," Zaluski reported. He predicts that this year's high cull rates contributed to the find.

Szymanski explained that a full epidemiological investigation involves both evaluating the extent of the disease and mitigating further spread. "I'm sitting on a list of 40 producers that I need to have conversations with. Although we are sifting through five years of brand records, we are moving as quickly as possible.

All this should be done by the middle of next week at the latest," she said. "However, this doesn't mean we have 40 herds to test. The concern will be with cattle that have had fence line contact or that have shared a pasture or common feeding, watering, or grazing sites. We're protecting the confidentiality of test data, so don't worry unless you get a call from us."

Because there is no successful vaccine and clinical signs or symptoms of this respiratory disease in animals are rare, options for TB affected herds are limited. They include whole herd depopulation or extended quarantine while the herd is repeatedly tested. USDA fund constraints dictate whether depopulation or testing out will be the option of choice.

In the first option, depopulation involves the slaughter of an entire herd. Producers subject to this extreme measure are reimbursed, or indemnified, by the federal government based upon assessment of the animals' value. Test negative animals from depopulated herds are able to go through slaughter channels in order to salvage the meat.

"Getting rid of an entire herd is an impactful measure," Zaluski stated, "and the intent of indemnity is not to make the producer whole but to reduce the impact. The USDA mitigates the impact with payments that cover the difference between the value of the animal and the amount collected from meat salvaged."

With extended quarantine, herds are subject to a series of live animal tests to diagnose additionally affected animals. In a process called testing out, these tests are repeated until zero animals are infected.

In response to a producer's concern, Zaluski confirmed that testing out does indeed make a herd chute shy and excitable, but that testing out applies only to a herd diagnosed as TB positive.

Zaluski provided a potential timeline for these processes. "We'll use the tail test first; that testing should be accomplished by next Thursday. If those tests aren't readily confirmed, we'll follow with a secondary test in the neck region during week two. A blood test will follow that. In the worst case scenario, we'll run a necropsy test in a month to a month and a half. We should be able to accomplish all these procedures by the middle of December."

From a public health standpoint, Montana Department of Livestock (MDOL) officials claim that although M. bovis is a zoonotic disease-one capable of infecting people-it is not a safety threat, thanks to a robust meat inspection program and the routine pasteurization of milk. Consumption of infected raw, unpasteurized, milk, however, is a documented route of transmission to people.

When someone in the crowd asked whether producers should voluntarily test their cattle for TB, Zaluski responded in the negative. "The likelihood of the disease is so rare, that unless there have been fence line contacts or that you have purchased animals from the source herd, we don't recommend that. We're being thorough and cautious, but the risk is low. So, unless you have a dairy herd-which should be periodically tested anyway; that's just good practice-widespread, voluntary herd testing is not cost effective or necessary."

Infection can also occur after exposure to foreign-born individuals; from direct contact with a wound, such as what might occur during slaughter or hunting; or through respiratory secretion-that is by inhaling the bacteria in air exhaled by animals infected with M. bovis or by coming into contact with their snot or saliva. Although direct transmission from animals to humans in these manners is thought to be rare, M. bovis can spread directly from person to person when those with the disease in their lungs cough or sneeze.

The MDOL will work with Montana Fish Wildlife and Parks and other wildlife services for the next two years to monitor coyotes, skunks, raccoons, rodents, and possibly prairie dogs. In addition, deer at check stations will not only be tested for Chronic Wasting Disease but for TB, as well.

Mike Honeycutt, Executive Director of the MDOL, told Thursday's crowd, "We are prepared to say with strong certainly that people wishing to purchase cattle from Blaine County producers should have no concerns. This circumstance is just a situation of bad luck. It says nothing negligent about the producer and is not a reflection of the State's cattle health. This should not affect the price of cattle in this county."

Zaluski added that the cooperation of area producers has been positive. "The people in Blaine County have been incredible to work with."

Anyone with questions about the bovine tuberculosis investigation is encouraged to contact the MDOL at 406-444-2043. The mission of the MDOL is to control and eradicate animal diseases, prevent the transmission of animal diseases to humans, and to protect the livestock industry from theft and predatory animals.