Bovine TB Would Cost Wisconsin Millions

By Ron Johnson Dairy Editor
Thursday, November 6, 2008 2:10 PM CST

What would happen if tuberculosis (TB) was found in a herd of Wisconsin dairy or beef cattle? State Veterinarian Bob Ehlenfeldt examined that question during last week’s Dairy Policy Summit of the Professional Dairy Producers of Wisconsin (PDPW).

To find an answer, Ehlenfeldt looked at what happened in other states that had to battle TB outbreaks.

“These outbreaks cost those states their TB-free status, cost their industries and the taxpayers millions of dollars, cost some of the producers their farms,” he related. “The unmeasured cost of TB or any other potentially zoonotic disease is the loss in consumer confidence.

“While recent discussions have focused on whether TB control is worth the economic cost, do we really want to go back to the time when it was a leading cause of human illness?” he asked. “Do we want to be responsible for any other human disease?”

One difficulty with TB is that it is “zoonotic,” meaning that it can spread from animals to people,” the veterinarian explained. Tuberculosis spreads to people by way of contaminated milk and meat.

“It has significant economic impacts on the livestock industry,” he emphasized. “In an earlier time the cost was in production losses. Today the industry feels the costs of control and testing.”

Tuberculosis is an Old World disease. It came to North America nearly five centuries ago with colonists from Europe. Just a century ago, TB was “a leading cause of death in humans, and 80 percent of those cases were the bovine form,” Ehlenfeldt noted. The disease is now “one of the reasons we require meat inspection and milk pasteurization,” he added.

Ehlenfeldt pointed out that cases of TB are not rare. In just the past three years, 10 states have reported cases.

Among them are two of Wisconsin’s nearest neighbors n Michigan and Minnesota. Other states with confirmed TB cases are South Dakota, California, Arizona, Colorado, New Mexico, Texas, Oklahoma, and Kansas.

Wisconsin has had cases of bovine TB, too. The last case was in 1997. Since then, the disease has been found in eight other states.

Michigan has the dubious honor of having the most TB cases, at 47. There, much of the problem is blamed on infected white-tailed deer, Ehlenfeldt said.

Minnesota has had 11 cases since 1997, followed by California with six and Texas with four.

One particular type of bovine TB is the “Mexican strain,” the veterinarian noted. This strain is problematic for U.S. agriculture because cattle from Mexico do enter the U.S.

Ehlenfeldt cited numbers from cattle inspection documents from the New Mexico Livestock Board. They show that in the 12 months from August of 2000 through 2001, more than 22,000 Mexican cattle were destined for Texas and New Mexico from just one entry port in New Mexico.

More than 2,000 others were headed for California, Arizona and Kansas. Still other Mexican cattle were headed to destinations as close to Wisconsin as Nebraska, Missouri and Iowa.

Wisconsin gets some positive responses to the caudal fold skin test that’s used to test cattle for TB. Ehlenfeldt said 3 percent of the Wisconsin cattle tested react as positive.

The Badger State’s large deer herd of one million-plus could also one day pose a TB problem such as that in Michigan. Warned the veterinarian, “No nation with documented wildlife reservoirs (of TB) has succeeded in eliminating the disease from wildlife or livestock.”

What might the cost of TB in Wisconsin be? Ehlenfeldt noted that the disease has cost Michigan farmers $277 million over the past decade.

In Minnesota, the bill has been between $1 million and $2.5 million in testing costs. Also in Minnesota, 45 farmers chose to let the state buy and slaughter their herds.

The indemnification cost in California is pegged at close to $60 million for three herds. In Wisconsin, testing individual animals for TB has run $1.8 million a year. For a case in 1995, a herd owner was paid $153,000 in indemnities.

If bovine TB was found in Wisconsin, many states would require that Wisconsin cattle be tested before they could legally cross the state’s borders, Ehlenfeldt explained. Also, animals that left the herd that was found to be infected would be tracked.

Link to Crohn’s?

The problems might not stop with tuberculosis. The state vet said it’s thought that there might be a link between another cattle disease and one that affects people. Maybe, he said, there’s a connection between Johne’s disease in cattle and Crohn’s disease in people.

If so, it could be a huge problem. Ehlenfeldt pointed out that a study last year by the National Animal Health Monitoring Service (NAHMS) found that 68 percent of U.S. dairy farms are “infected with Johne’s disease.”

By contrast, a century ago, TB infected just 5 percent of U.S. cattle herds, but still caused widespread disease in people.

“If we ever find that it (Johne’s) is zoonotic, what will that mean for human health?” Ehlenfeldt asked. “And what will that mean for your pocketbook?”

A dairy co-op in Oregon, Tilamook Cheese, mandates that the herds of all its member-farmers must be tested yearly for Johne’s. That’s done because, “Healthy cows produce better milk. Better milk makes better cheese,” Ehlenfeldt said.

The dairy industry has two choices with Johne’s disease, according to the state veterinarian. It can “look the other way and hope it goes away” or it can “address the disease and move ahead.”

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