Johne's awareness climbs among producers

FORT COLLINS, COLO. - Just one percent of producers at dairy operations are unaware of Johne's disease, down 10 percent in 1996. Yet those same producers are lax when it comes to biosecurity.

That's according to the latest National Animal Health Monitoring System (NAHMS) report titled "Dairy 2002: Johne's Disease on U.S. Dairy Operations." Recently released, the report highlights 21 major dairy states and data from 83 percent of U.S. dairy operations and 85.7 percent of the nation's dairy cows. The information was collected between Feb. 2002 and Jan. 2003.

As far as Johne's disease education is concerned, study author Dr. Jason Lombard says he's impressed. Universities and veterinarians have done a lot of work, he says.

"The number of producers who reported they're knowledgeable about Johne's disease has tripled since 1996," says Lombard, a USDA veterinary epidemiologist. "We're never going to get everyone, but this ongoing education seems to be working pretty well." (See Table 1)

Table 1 Percentage of operations by level of familiarity with Johnes disease in 1996 and 2002, by herd size

Dairy farm biosecurity

When it comes to biosecurity, ongoing education seemingly fails to garner results. According to the report, studies associate herd additions with Johne's disease infections. Still, most U.S. dairy operations fail to adopt biosecurity practices such as quarantining new animals and testing for

Myco-bacterium avium paratuberculosis

(MAP), the agent responsible for Johne's disease, the report shows. (See Table 2)

"Careful scrutiny of the source of new additions and brief isolation or quarantine once the animals are on the dairy are good management practices," the report says. "Although biosecurity recommendations regarding purchase of herd additions have been published, dairy producers in the United States and other countries have not embraced these practices."

There was no difference between 1996 and 2002 in the reported percentage of operations that required testing for MAP infection prior to bringing animals onto the operation, the report adds.

dvm Newsbreak

Lax biosecurity is not a reflection on the veterinary profession, Lombard says.

"Most veterinarians are discussing biosecurity in general with dairy farms on a routine basis," he says. "When we look at implementation of some biosecurity practices, we would like to see producers adopt more quickly. Veterinarians are in a position where they can give recommendations, but they aren't necessarily involved at a management level."

Vaccine use

When it comes to vaccines, veterinarians are very involved yet most producers aren't using inoculation as a means to prevent MAP. According to the report, numbers of producers using the vaccine decreased from 5.4 percent in 1996 to 4.6 percent in 2002.

While the report maintains vaccination is "a viable tool" for preventing Johne's disease infection, Lombard says lack of use hinges on the drug's efficacy.

"The literature is mixed when it comes to whether or not the vaccine reduces shedding of the organism; there is strong evidence it can interfere with (tuberculosis) testing," he says. "Some states such as Colorado don't allow its use."

Accidental self-injection is a problem for DVMs, the report says. "There have been reports in the literature of veterinarians having reactions," Lombard says. "How prevalent that is, I don't really know."

Up to producers

Whether or not producers do more to deter Johne's disease infection remains to be seen, but they won't be forced by the federal government to act, Lombard says.

"It's not a regulatory disease so the producer is not required to do anything specifically," he says. "The only federal regulations currently in place don't allow interstate movement of animals that are fecal culture positive for Mycobacterium avium paratuberculosis. It is really up to the producer and their veterinarians to determine which biosecurity measures to adopt."