Prions, found in the brains of animals with brain wasting diseases, could be spread through urine. © SPL
Posted on 10/18/2005 12:23:50 AM PDT by neverdem
Mystery of infections in deer and elk may have a solution.
The protein particles that cause illnesses such as mad cow disease can be found in the urine of infected mice, researchers report.
Their study may solve the mystery of how such 'prion' diseases spread among animals such as sheep, elk and deer. But it also raises concerns that the urine of humans with variant Creutzfeldt-Jakob disease (vCJD) may contain dangerous proteins.
Prions are primarily found in the brain, the spinal cord and the immune system. British cows are thought to have developed the prion disease bovine spongiform encephalopathy (BSE) by eating ground-up brains, spleens and similar material. Other body parts were thought to be relatively safe for consumption.
Then, in 2003, Adriano Aguzzi's group at the University Hospital of Zurich, Switzerland, found prions in the muscle tissue of people who had died from a brain wasting disease. And this January, the team showed in mice that prions also spread to the pancreas, kidneys and liver if there is inflammation in these organs. Together, these findings suggested that the brain and lymphatic organs might not be the only dangerous ones.
Now, Aguzzi and his colleagues have raised further concerns in a paper in Science1.
Protein injection
The researchers took mice with a chronic inflammation of the kidney and infected them with prions. They then concentrated the proteins in their urine tenfold and injected the mixture into the brains of healthy mice. This treatment made the mice sick.
"We knew that we had something really exciting on our hands," Aguzzi says. "I couldn't believe it."
An injection of concentrated proteins from one millilitre of urine caused prion disease in half of the treated mice, Aguzzi says.
The research may explain how animals such as sheep, elk and deer transmit prion diseases. In the United States, a chronic wasting disease is spreading "like wildfire" among elk and deer, says Aguzzi. About 20% of the wild deer in some parts of Colorado are infected, says Aguzzi, and yet these animals are herbivores.
"Nobody understands what controls the spread," says Aguzzi. Dust mites have been suggested as one method of transmission. Aguzzi adds that animals may be eating urine-contaminated grass.
Low doses
An explanation that involves urine has difficulties however. The concentration of prions found in the mouse urine in the experiment was 10,000 times lower than in the lymphatic organs, and a million times less than in the brains, the original site of infection.
Neil Cashman, a prion researcher at the University of British Columbia in Vancouver, says that the risk of getting sick by touching or ingesting infected urine is minuscule. He explains that, quite apart from the low concentration of prions in urine, it would take a higher dose of the proteins to cause infection this way than through injection into the brain.
As yet, there are no data on the risk that might be attached to contact with urine from vCJD patients. On the other hand, says Cashman, "nobody wants human prions in the hospital laundry".
References: doi:10.1038/news051010-13
Seeger H. et al. Science, 310. 324 - 326 (2005)
Prions, found in the brains of animals with brain wasting diseases, could be spread through urine. © SPL
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"Then, in 2003, Adriano Aguzzi's group at the University Hospital of Zurich, Switzerland, found prions in the muscle tissue of people who had died from a brain wasting disease."
Are cows any different?
It all reminds me of Ice-9.
I don't know. I entered bovine myocytes AND prions into PubMed. This was the only result. PrPSc accumulation in myocytes from sheep incubating natural scrapie. Click "Related Articles" if you go to the PubMed link.
What's Ice-9?
From the book by Kurt Vonnegut called Cat's Cradle.
The Scientologists Were RIGHT!
What does that mean? How so?
That news should be widely circulated. Deer hunters might want to forgo their venison for a long time.
Well, to wax colloquially here, there IS the old tale that goes: if a mouse runs over you while you're reclining and urinates on you, you're going to be very sick (and some people think it means death, not illness, will occur).
Might be something to that, afterall.
To my knowledge, this has never actually been proven to causality, just coincidence.
Don't eat yellow snow.
There had to be a reason like this why Chronic Wasting Desease (CWD) spreads so easily in deer, elk and moose populations.
Any farm that has seen an infection can never have deer or elk reintroduced since the desease seems to stay in the soil for years. In the wild, once the desease in introduced in an area, it just seems to continue spreading.
Deer and elk are more apt to smell each other's urine as part of their natural habits so if the prions are in found in urine, it seems this is the path that spreads the infection.
We have not seen infection rates like there is in CWD (the deer and elk version of the desease) in other prion deseases like mad cow, scrapie and CJD in humans so this research is probably more relevant for CWD only.
The idea that prions could possibly be found in the muscles of bovines is exceedingly frightening.
Interesting ping
"The idea that prions could possibly be found in the muscles of bovines is exceedingly frightening."
Yes it is.
I'm a heavy meat eater.
Makes one wonder...
I don't fully understand why this problem hasn't been totally eliminated by now. The consequences are too serious not to.
There was an article posted here sometime back saying that back when all this began in Britain, that Britain was buying "protein mass" in bulk from India. And that it contained human remains...
Very sick.
Yes it is. Now go out and enjoy those steaks and burgers, if you can.
I would step away from some of that meat, if I were you.
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