First U.S. Resident Diagnosed With Mad Cow

What is believed to be the first case of mad cow disease in a resident of the United States has been diagnosed in a 22-year-old British citizen living in Florida, state and federal officials said today.

The Florida Department of Health and the federal Centers for Disease Control and Prevention are investigating the likely case of the form of mad cow disease that infects humans, called "new variant Creutzfeldt-Jakob Disease."

The diagnosis of the brain-destroying illness was made at a hospital in England, and the woman has since returned to the United States with her family, the CDC said this evening.

The victim, who was raised in England and recently moved to the United States, is believed to have contracted the disease in England at the peak of the mad cow outbreak there, said the CDC's Dr. Steve Ostroff.

"There's every reason to suspect that she acquired her illness there," he said.

'No Threat to Anyone Else'

There is no reason to fear cattle in the United States have the cow version of the illness, known as bovine spongiform encephalopathy or BSE, officials with the Florida Department of Health said.

"All evidence indicates her illness poses no threat to anyone else or the agriculture industry," state Department of Health spokesman Bill Parizek said.

The only way to confirm the diagnosis is through a brain biopsy or in an autopsy.

New variant Creutzfeldt-Jakob is a rare, degenerative, fatal brain disorder that emerged in the United Kingdom in the mid-1990s, and has spread around Europe, doubling every 3 1/2 years. As of the start of this month, 125 cases had been confirmed, including 117 in England, six in France, and one each in Ireland and Italy, the CDC said.

The standard form of Creutzfeldt-Jakob Disease is more common, and is already known in the United States.

The CDC said there is no evidence that the vCJD has ever been transmitted from person to person. It is believed to spread from eating cattle products contaminated with the agent that causes it.

No case of this disease has ever been identified in the United States by the Department of Agriculture, which tested 5,200 cattle brains last year and plans to test 12,500 this year.

Officials declined to comment on the condition of the infected woman, citing her privacy, but said she had not yet reached the end-stage of the disease, for which there is no known cure.

The outbreak in England devastated the country's cattle industry.

ABCNEWS' Lynne Adrine and Mary Harris contibuted to this report.