Mad cow type diseases may spread in urine-study

By Maggie Fox, Health and Science Correspondent

WASHINGTON (Reuters) – The agent that causes mad cow
disease, scrapie and chronic wasting disease in deer and elk
may sometimes be spread through urine, Swiss researchers
reported on Thursday.

They found that, under certain conditions in mice, the
deformed brain proteins known as prions that transmit the
disease could be found in urine.

“We tested whether chronic inflammatory kidney disorders
would trigger excretion of prion infectivity into urine,”
Adriano Aguzzi of the University Hospital of Zurich and
colleagues wrote in their report, published in the journal
Science.

Scrapie-infected mice with kidney inflammation excreted
prions in their urine, and these prions infected other mice
with scrapie when injected, Aguzzi and colleagues found.

It is a long way from this laboratory experiment to a
real-world setting in which grazing or browsing animals pick up
and become infected with urine from others, but the researchers
say it shows such transmission is theoretically possible.

Aguzzi, an expert in prion diseases, and his colleagues
said the finding could help explain how wild deer and elk in
western U.S. states and elsewhere are becoming infected with
chronic wasting disease.

It might also explain how scrapie is spread among sheep.

These diseases, known as transmissible spongiform
encephalopathies, or TSEs, include bovine spongiform
encephalopathy (BSE or mad cow disease), scrapie and, in
humans, Creutzfeldt-Jakob disease or CJD.

The diseases are caused by a deformed version of a brain
protein called a prion, which is harder to destroy than a virus
or bacteria and can spread from animal to animal.

Scrapie has existed for hundreds of years in sheep and was
never known to infect another species. In the 1980s, BSE broke
out among British cattle and was eventually traced to feed that
may have contained the remains of scrapie-infected sheep.

Later, people who ate beef began to develop a version of
CJD that has been linked to BSE-infected meat. Called nvCJD, it
is different from ordinary CJD and has killed 151 people in
Britain so far and a handful in other countries.

Normally, CJD, which has no known cause and no cure,
affects about one in a million people globally.

All the diseases gradually destroy the brain and cause
death. There is no treatment.

Agriculture officials around the world have changed the
rules on animal feed, but cases of BSE still occur on occasion,
causing panic among cattle traders and sometimes disrupting the
cattle products trade.

Cosmetics and pharmaceuticals made using beef products are
now checked for components that could transmit the prions,
including brain, nerve matter, spleen and other organs. The
researchers suggest that urine might be added to the list of
watched-for products.

Aguzzi’s team said the mouse urine did not contain prions
when they did not have kidney inflammation. But they said
inflammatory kidney conditions caused by bacteria, viruses or
autoimmune diseases are common and noted that they can also be
associated with advanced dementia — a symptom of CJD.

They also said one team has reported finding prions in the
urine of a CJD patient and another team infected mice with CJD
by injecting them with urine from one CJD patient.