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Subj: Study shows how mad cow disease gets to brain

Date: 3/30/99 10:53:36 AM Eastern Standard Time

From: hansmi@... (Hansen, )

> Headline: Study Shows How Mad Cow Disease Gets To Brain

> Wire Service: RTos (Reuters Online Service)

> Date: Tue, Mar 30, 1999

>

> Copyright 1999 Reuters Ltd. All rights reserved.

> The following news report may not be republished or redistributed, in

> whole

> or in part, without the prior written consent of Reuters Ltd.

>

> By Maggie Fox, Health and Science Correspondent

> WASHINGTON (Reuters) - Researchers said Monday they had documented

> how the agent that causes mad cow disease gets from food into the brain.

> It travels from the digestive tract into the lymphatic system and

> from there into the brain, they reported in the Proceedings of the

> National Academy of Sciences.

> They also said they had shown, to no one's surprise, that primates --

> the family that includes human beings -- can be infected with mad cow

> disease from food.

> " It tells us that under natural conditions, natural including zoos,

> that primates can be infected. That doesn't come as a surprise, "

> Brown of the National Institute of Neurological Diseases and Stroke in

> Bethesda, land, said in a telephone interview.

> Mad cow disease, known officially as bovine spongiform encephalopathy

> (BSE), swept through British cattle herds in the 1980s. It was traced to

> feed made of the remains of sheep that had been infected with scrapie,

> their version of the disease.

> It is caused by a mutated version of a protein known as a prion,

> which is very resistant to destruction by cooking or chemicals.

> At first British officials said there was no risk to people from

> eating beef, but now 39 people are known to have died from a human version

> of mad cow disease caught from infected beef.

> It is a close relative of Creutzfeldt-Jakob disease (CJD), a

> naturally occurring disease that kills about one in a million people. No

> one knows what causes CJD, but the new version, known as new variant CJD

> or nvCJD, is blamed on infected beef.

> Brown and colleagues at Montpellier University in France, reported

> several cases of a related disease in lemurs.

> Zoo animals fed the same supplements as British cattle are known to

> have died of transmissible spongiform encephalopathies, which literally

> turn the brain into a sponge. Animals killed by the spongiform

> encephalopathies range from mink to antelope. Domestic cats have died of

> them, too.

> The Montpellier team fed cattle brain to three lemurs -- two got two

> small meals containing the brains and one got a single meal with the

> brains.

> Lemurs fed the cattle brains had the abnormal prions in their

> tonsils, digestive tracts, spleen and lymph system, as well as in their

> spinal cords and brains, they reported.

> They said similar patterns were seen in 20 lemurs that had been fed

> beef protein made by a British company, two of which showed symptoms of

> the brain disease.

> The pattern, they said, was clear -- the infection moves from the

> digestive tract to the lymphatic system, including the tonsils, then to

> the spinal cord and brain.

> " Our observations also show that even before (the abnormal prions)

> can be detected in the central nervous system in the pattern typical of

> terminal illness, it can be traced along nerve pathways ... through the

> spinal cord and into the brain cortex, " they wrote.

> Such infections could be more widespread than anyone thought and they

> recommend close monitoring of zoo animals.

> " This really documents, in great precision, a route by which the

> infectious agent enters the body from the mouth. This is all occurring

> early in the incubation period, " Brown said.

> " To see the abnormal protein in the coverings of the mucus membranes

> of the gut and .. see how it transfers to the gut wall and gets into the

> spleen and goes from the spleen into the spinal cord and up the spinal

> cord into the brain is a very pretty picture of the route, " he said.

> Brown said the study explained why the infectious prions can be found

> in the tonsils of victims.

> " It is not because this is some heated-up variety (of CJD) but simply

> because it entered the body through the mouth. That's good news, " he said.

> Because CJD has such a long incubation period in humans, Brown said

> it is still far to early to tell whether the nvCJD will cause a serious

> epidemic in Britain.

> Tonsil tests will probably show who has CJD incubating in their

> bodies, Brown said, but he does not recommend doing them.

> " You tell me what good it would do, " he said. All forms of CJD are

> incurable and always fatal.