Scientists Discover New Form
Of Mad Cow Disease
The Scotsman - UK
2-17-4
{PA News) -- Italian scientists have found a second form
of so-called "mad cow disease" that more closely resembles the
human Creutzfeldt-Jakob disease than does the usual cow form of the illness.
The brain-wasting diseases BSE, known as mad cow disease,
and human CJD are caused by different forms of mutant proteins called prions.
A number of people, mainly in Britain, have also suffered from what is
called variant CJD, a brain disease believed to be acquired by eating meat
from infected cows (vCJD).
Now, the team of Italian researchers reports a study
of eight cows with mad cow disease found that two of them had brain damage
resembling that in the human victims of CJD. They said the cows were infected
with prions that resembled those involved in the standard form of the human
disease, called sporadic CJD, not the variant caused by eating infected
meat.
Salvatore Monaco, lead author of the new study, said
the findings may indicate that cattle can also develop a sporadic form
of the disease, but it might also be a new foodborne form of the illness.
Dr Paul Brown of the National Institutes of Health in
the US said the finding does not indicate an increased threat to humans.
If a new form of the disease were affecting humans, there
should be an increase in the incidence of CJD, said Dr Brown, who was not
part of the research team.
But scientists in Europe have studied all cases of sporadic
CJD for the past decade and the incidence has not changed, said Dr Brown,
an expert in the disease who works at the US National Institute of Neurological
Disease and Stroke.
Both the human and cattle diseases cause holes to form
in the brain. The Italian researchers found that, in addition to the holes,
two cows had an accumulation of amyloid plaque in their brains. Amyloid
plaques are an indication of Alzheimer's disease in humans. They have also
been found in people with sporadic CJD but had not been found in cattle,
the researchers said.
Mad cow disease is formally known as BSE ñ bovine
spongiform encephalophy ñ and the Italians named the new form with
amyloid plaques BASE.
"Although observed in only two cattle, the BASE
phenotype could be more common than expected," they reported.
Mr Monaco said that he believes the incidence could be
as high as 5% among cattle with mad cow symptoms.
But while human CJD and BASE share several characteristics,
the Italian researchers warned against assuming a link between the two.
The findings of the team led by Mr Monaco, of the Department
of Neurological and Visual Science, Policlinico G.B. Rossi, in Verona,
Italy, are reported in this week's online edition of Proceedings of the
National Academy of Science.
Dr Brown said there also have been some unpublished reports
from Japan of cows with a different form of mad cow disease.
Cattle are believed to develop BSE from eating infected
tissues of other animals. Such feed has now been banned in many countries.
