Mad cow fears mount

By Chris Morris
The Edmonton Sun
January 19, 2004

Human disease may be scarier than first thought

New research suggests that the human form of mad cow disease is a lot more
complicated than originally thought, and, potentially, much scarier.

Scientists have long agreed that eating cattle tissue infected with bovine
spongiform encephalopathy - mad cow disease - can cause the human form of
the disease, known as variant Creutzfeld-Jacob disease.

But recent animal tests indicate that eating infected beef may also cause
another form of the disease, classical CJD, forcing scientists to re-examine
assumptions about the nature of the deadly disease and raising fears that it
may be more widespread than previously thought.

"We have to be a little bit open-minded about this," says Dr. Laura
Manuelidis, professor and head of neuropathology at Yale University in
Connecticut.

"There are certain things we don't know and we can't be absolute about. We
can't make believe it's a cut-and-dried situation."

The accepted wisdom has been that classical CJD has nothing to do with mad
cows. It affects older people, those over 55, and generally occurs
spontaneously at the rate of about one person per million per year.

It has been confused with Alzheimer's disease and there is some concern that
because of misdiagnosis, it may be more widespread than the confirmed
numbers indicate.

"The fact is in the United States, the autopsy rate has gone way down from
when I was a medical student, even in academic centres," says Manuelidis.

"If you don't examine the brains, how can you possibly know what you are
missing?"

Manuelidis says a recent study in Britain involving mice whose brains were
genetically engineered with human genes gives weight to her long-held theory
that classical CJD may be more insidious than assumed. The mice were
injected with tissue from mad cows. One set of mice fell sick with the human
form of mad cow, or variant CJD.

But, in a finding that shocked researchers, a few of the mice developed what
looked like classical CJD, the form scientists have long believed had no
relationship to mad cows or eating meat.

Dr. Neil Cashman of the University of Toronto describes the findings as
"striking and worrisome."