By MATTHEW WEAVER
National animal disease experts say the Washington Department of Agriculture is taking the correct steps in investigating a possible case of bovine tuberculosis.
"It seems like a textbook case," said Jamie Jonker, vice president of scientific and regulatory affairs for the National Milk Producers Federation.
The disease is primarily spread by respiratory secretions between animals.
USDA and the state involved usually conduct testing, Jonker said. If bovine TB is confirmed, the animal is traced back to its herd of origin and testing conducted on any animal that may have been exposed.
The government typically either slaughters the entire herd or tests them for potential reaction, removing those that show initial signs for further testing, Jonker said. The latter practice takes longer, but allows the farmer to keep animals that are free of disease.
Jonker recommends farmers ensure they have good biosecurity and follow practices on their farm to prevent the introduction or spread of the disease, including knowing the health status of new animals before bringing them onto the premises.
The disease is nearly eradicated in the United States cattle population, Jonker said. Occasionally a case arises in beef or dairy cows in California, New Mexico and Texas during the last decade, Jonker said.
In Michigan, bovine TB has become established in restricted populations of white-tailed deer in the northeastern part of the state, said Steve Schmitt, wildlife veterinarian for the Michigan Department of Natural Resources.
Schmitt estimated 55 cattle herds have been infected with bovine TB since 1998, some more than once, because the disease is still in the wildlife population. Most infected herds had only one animal infected, he said.
Ranchers fence their feeding areas or locate them near their barns to keep deer away. Moving cattle is restricted in infected areas, and there are testing requirements to catch signs early, Schmitt said.
The state and USDA have spent $200 million to combat bovine TB, he said.
Schmitt said it's unlikely the disease will ever be eradicated in Michigan, even though a relatively small percentage of the deer, about 1.5 percent, are infected.
There's very low risk of humans becoming infected, Schmitt said. Pasteurization kills the bacteria in milk, though there's been one instance in Michigan of a hunter contracting the disease from a deer. In that case, the hunter cut open an infected animal's lesion, then poked himself in the finger with a knife.
It takes daily doses of antibiotics for six months to a year to cure an infected human or animal, Schmitt said.
"It's not so much a public health problem, it's more of a concern for market access," he said. "You don't want to obviously have a known cattle herd infected that you're not doing anything about."
National Milk Producers Federation: www.nmpf.org
Michigan Department of Natural Resources: www.michigan.gov/dnr/0,1607,7-153-10319-99064--,00.html