[R-G] Fw: Research in Italy Turns Up a New Form of Mad Cow Disease

[Tim Murphy]

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Research in Italy Turns Up a New Form of Mad Cow Disease
February 17, 2004
Research in Italy Turns Up a New Form of Mad Cow Disease
By DONALD G. McNEIL Jr.
http://www.nytimes.com/2004/02/17/health/17COW.html

A new form of mad cow disease has been found in Italy, according to a study
released yesterday, and scientists believe that it may be the cause of some
cases of human brain-wasting disease.
While the strain has been found in only two Italian cows, both apparently
healthy, scientists in Europe and the United States said it should provide
new impetus in Washington for the Department of Agriculture to adopt the
more sensitive rapid tests used in Europe because it may not show up in
those used in the United States.
Along with the Italian study, there have been recent reports of unusual
types of mad cow disease in France and Japan, and scientists say the
discovery of new forms suggests that many cases of "sporadic" human
disease - by far the most common kind, responsible for about 300 deaths a
year in the United States - are not spontaneous at all, but come from eating
animals.
The brain-destroying diseases involve prions - misfolded proteins that are
believed somehow to induce other proteins to fold incorrectly, leaving
patches of useless debris and holes that turn brains to sponge.
The study, by a team from universities in Turin, Verona, Brescia and Milan,
was edited by Dr. Stanley B. Prusiner, who won a 1997 Nobel Prize for his
prion work. It appears this week in The Proceedings of the National Academy
of Sciences.
Two American experts not involved in the study said the findings were
sobering. Dr. Pierluigi Gambetti, director of the National Prion Disease
Pathology Surveillance Center at Case Western Reserve University, called the
report "very convincing." Dr. Paul Brown, a prion expert at the National
Institutes of Health, said it "opens the possibility of a second strain of
the agent in circulation - and that's probably not good news."
Current American testing focuses only on finding the prion that causes
bovine spongiform encephalopathy in cows and "variant" Creutzfeldt-Jakob
disease in humans.
But the disease found in two aged dairy cows in Italy is so different that
its discoverers gave it a new name, bovine amyloidotic spongiform
encephalopathy, or BASE, because it forms amyloid plaques in the brain -
round, dark clumps of sticky protein junk.
"We don't know if this disease is passed to humans," said Dr. Salvatore
Monaco, a neurologist at the G. B. Rossi Polyclinic in Verona and an author
of the study. "But it is very similar to a subtype that causes sporadic
C.J.D. in humans."
In the past, some people with cases diagnosed as sporadic have said they ate
squirrel brains, pig brains or raw meat, but no link to a different prion
was established, said Dr. Michael C. Hansen, who studies prion diseases for
Consumers Union. Recently, he said, a new prion strain closely related to a
French strain of scrapie, a sheep disease, was found in a French cow.
Both the Italian cows, one 15 years old and one 11, appeared healthy. Their
unusual strain was discovered only because Italy tests all cattle over 30
months old slaughtered for human food. By last August, it had tested 1.6
million and found 103 that tested positive for prions.
Finding a new strain in apparently healthy cattle "suggests that all
surveillance should be like we do in Italy," Dr. Monaco said.
Many American prion experts concur. The United States now plans to test only
40,000 cows this year, focusing on those too sick to walk, and using an
immunohistochemistry test that takes about eight days and is "much less
sensitive," Dr. Gambetti said, than tests used in Europe that take only
hours.
Besides forming plaques, the strain differs in that it appears in much older
cattle. Most cows with the well-known strain die before they are 10. Also,
the new prions collect in different parts of the brain - the olfactory bulb
and thalamus, rather than the brain stem. The two cows also had relatively
fewer "holes."
Those characteristics resemble the ones found in about 30 percent of humans
who have the sporadic form of Creutzfeldt-Jakob disease.
In the United States, about one person per million develops and dies of the
sporadic form each year, meaning that there are usually about 300 cases in
the country. (For unknown reasons, Italy has nearly two cases per million;
Switzerland has about three.)
Only one person in the United States has had variant Creutzfeldt-Jakob, the
human form of mad cow disease, which was first described in the 1990's and
has killed about 150 Europeans; she grew up in Britain and was probably
infected there.
Most sporadic cases are among the elderly, while in Britain the variant form
struck many people under 30. Victims of both rapidly develop staggering,
memory loss and dementia, fall into comas and die.
Dr. Brown said the discovery did not suggest that many humans were suffering
from undiagnosed illness. If that was the case, he said, the number of
sporadic cases found in Britain since 1994 should have shot up; they have
not.
The sporadic form has been assumed to arise spontaneously because there has
been no other obvious cause, said Dr. Laura Manuelidis, a Yale
neuropathologist who studies the disease.
But human cases from several countries produce different symptoms when
injected into susceptible mice, showing that there are several human
strains.
Dr. Manuelidis is skeptical of the conventional wisdom that prions, which
contain no DNA or RNA, can transmit infections. She believes that a
slow-acting virus, not yet discovered, may be the cause.
To make her point that such infections may have been crossing species well
before mad cows created a scandal in Britain a decade ago, she read from an
old report she has posted on her office door.
It is from an 1883 issue of the Medical Veterinary Review: A veterinarian
named Serraet from southwest France describes a cow he saw die of the
symptoms of scrapie, which had then been known in sheep for 100 years:
itching, nervousness, partial paralysis and, ultimately, coma.
Dr. Serraet ends with a suggestion: "I would advise the managers of cattle
abattoirs to sell the meat only to lower-class butcher shops."

Copyright 2004 The New York Times Company

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