A second case of mad cow disease may have occurred in the United States, Agriculture Department officials said Thursday.

They said it would need four to seven days before confirmation by further tests of brain tissue samples from the suspicious cattle. They refused to disclose where the possibly new case was found. The possible case comes 11 months following the report of first case in the United States.

Mad cow disease, or bovine spongiform encephalopathy (BSE), is a deadly animal epidemic that attacks the animal's nervous system. People who eat food contaminated with the disease can develop a human equivalent, variant Creutzfeldt-Jakob disease.

"Early this morning, we were notified that an inconclusive BSE test result was received on a rapid screening test used as part of our enhanced BSE surveillance program. The inconclusive result does not mean we have found another case of BSE in this country", said a Department statement on net.

"Inconclusive results are a normal component of screening tests,which are designed to be extremely sensitive so they will detect any sample that could possibly be positive," said Andrea Morgan, Associate Deputy Administrator of the USDA's Animal and Plant Health Inspection Service, in the statement.

Last summer, further and more sophisticated tests had found twoinconclusive tests to be eventually negative. After the report of first BSE case, the United States set up a surveillance program involving rapid tests to detect BSE and prevent its spread. The program aims to test more than 220,000 cattle by the end of 2005. The USDA had until last Sunday tested 113,264 cattle under the newsurveillance program.

Japan and other countries have been banning imports of US beef and beef products since the first BSE case in the United States.

Source: Xinhua