Threat of mad cow disease tests effectiveness of nation's biosecurity

University Park, Pa. -- With the most recent threat of mad cow disease on American soil revealed as a false alarm, a specialist in Penn State's College of Agricultural Sciences says consumers still can have confidence that the nation's beef supply is safe.

The headlines surrounding the recent U.S. Department of Agriculture announcement of inconclusive test results for bovine spongiform encephalopathy or BSE -- popularly known as mad cow disease -- have some consumers wondering if the nation's beef supply is well protected. John Comerford, associate professor of dairy and animal science, says he's surprised by the media attention generated by the testing, since it's not unusual for a false positive to occur.

"This was the third time that USDA testing procedures have produced an inconclusive test since June of this year," he says. "The animal tissue is sent for more intensive testing in Iowa, where the samples were all found to be negative. The initial test is screened at the local processor, so there's always a possibility of another positive test, but the fact that the process is working is what's important.

"Scientists and human health officials pretty much agree that BSE is really an animal-health industry problem because it will ultimately have a profound effect for beef producers in terms of economics, credibility, marketing, processing methods and other factors. Most of the scientific community agrees that the probabilities of someone getting sick from eating beef with BSE -- even from a known infected cow -- are very remote. And the industry is closely attuned to ensuring that unsafe animals are identified and removed from the food chain because it's best for their business."

Comerford says the age of most cattle used for beef -- coupled with screening tests aimed at high-risk animals -- provides safeguards to protect the American food supply.

"Only about 20 percent of the animals that are processed for food are susceptible to BSE," Comerford says. "That's why we only test a small proportion of the animals harvested -- many of them can't have BSE. We've never identified BSE in an animal less than six to eight years of age. Most of the retail beef that you would find in the grocery store, for example, comes from animals that are under 30 months of age. So, the chances of any of those animals having BSE are extremely remote."

The beef supply soon will be even safer, Comerford says, as a new voluntary state and federal system will assign tracking information to all beef animals and production locations, so that BSE and other diseases can be isolated and eliminated from the national beef herd more quickly.

"Every beef animal will have a unique identification that will be entered into a centralized database along with the farm or location of origin," he says. "Pennsylvania's Department of Agriculture and the Pennsylvania Beef Council are leading that effort in a beta-testing procedure for mandatory animal and premise identification. It's going to take time -- individually identifying a few million animals and knowing where they are at any given time can't happen overnight. The industry is very interested in making this happen, but it's a large job to work out the logistics of recording the identification and transferring information to the database. The other issue is deciding who will have access to the information."

Many European nations already have individual animal identification systems, Comerford says, but an American system presents unique demands and challenges.

"American beef cattle move around a lot," he explains. "They may go to summer pasture in the mountains of Montana, spend the winter in Texas, and then be fed grain rations in Kansas or Oklahoma. The geographical spread is part of the challenge of making mandatory identification work."

Comerford says the important point for consumers is that the existing system of surveillance and screening tests is working to prevent any potentially harmful meat from entering the food chain. "The American consumer can be confident that their beef is safe, because all of the testing procedures and 'firewalls' have worked," he says.