U.S. officials say they could learn early next week whether cows imported to the United States from Canada are infected with mad cow disease, a fatal neurological disease that can spread to humans who eat contaminated beef.

U.S. agriculture officials have now located nine cows out of herd of 82 head of cattle imported from Alberta, Canada that may be infected with mad cow disease.

The animals were sent to a ranch in Washington state, where one of the cows, infected with bovine spongiform encephalopathy (BSE), was discovered earlier this month.

Department of Agriculture chief veterinarian Ron deHaven said officials could soon know whether the other eight animals, whose DNA is being tested at labs in the United States and Canada, are also infected with BSE. "Assuming no laboratory glitches, we could have results from both laboratories early next week," he explained. Dr. deHaven pointed out that stricter inspection measures announced Tuesday could help determine within two days whether apparently sick cows, known as "downers," are infected with mad cow disease. He said one measure, to quarantine downer cows while they are being tested, went into effect immediately after the announcement.

And meatpackers have now stopped using a slaughtering method that can contaminate meat with infected parts of a sick cow.