Risk of U.S. mad cow outbreak remains low

There's a remote possibility mad cow disease (bovine spongiform encephalopathy) landed in the U.S. undetected from imported British cattle in the 1980s, according to Harvard University researchers cited in a Food Safety Network newsletter.

The bright side, the scientists report, is that government preventive measures would have contained the disease from spreading.

In their study, researchers say it is "extremely unlikely" the disease will ever take over U.S. herds, especially because of a 1997 ban on the use of meat and bone meal in cattle feed. Since then, the U.S. is beefing up preventive tactics to include restrictions on animal feed and meat processing.

The Harvard study, based on mathematical models, states that there is an 18 percent chance mad cow was introduced into the country before imports of British cattle were banned in 1999. The likelihood of those cattle spreading the disease is virtually nil.