Ever wonder why the deer in New York, Michigan etc keep have larger and larger populations of animals with “mad cow disease”.  Scientist think they have the answer, and it doesn’t look all that good for the population at large.  Below is an excerpt, but click on more and read the whole story.

Contamination of soil with urinary prions may contribute to spreading prion disease among animals, which are known to ingest large amounts of soil, including cattle, sheep and cervids. Worrisomely, the continuous excretion of urine and the extremely high resistance of prions may lead to a progressive accumulation of infectious material in the environment, with potentially catastrophic consequences in the future.

So you say “So What?”   Well this has a direct impact on humans and the food they consume.

“One of the top priorities in the prion field is to minimize further spreading of TSEs to humans or animals by limiting the exposure to contaminated material. This is a difficult problem, because prion diseases have a long clinically-silent incubation period in which infected individuals may unknowingly transmit the disease.

Finding prions in urine just made that job  (a job that was already extremely difficult) a million times harder.  Blog in, and tell us what you think those “catastrophic” consequences in the future might be!

Detection of infectious prions in urine
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Abstract
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Prions are the infectious agents responsible for prion diseases, which appear to be composed exclusively of the misfolded prion protein (PrP(Sc)). The mechanism of prion transmission is unknown. In this study, we attempted to detect prions in urine of experimentally infected animals [hamster].

PrP(Sc) was detected in approximately 80 per cent of the animals studied, whereas no false positives were observed among the control animals. Semi-quantitative calculations suggest that PrP(Sc) concentration in urine is around 10-fold lower than in blood. Interestingly, PrP(Sc) present in urine maintains its infectious properties. Our data indicate that low quantities of infectious prions are excreted in the urine. These findings suggest that urine is a possible source of prion transmission.

The following paragraphs are extracts from the Discussion section of this paper:

“PrPSc in urine retains infectious properties, since injection of the agent amplified from this fluid produced a disease indistinguishable from the one induced by in vivo isolated material. Interestingly, animals [hamsters] inoculated with PrPSc amplified from the HY strain (both from brain and urine) showed a similar incubation time as those injected with the same quantity of PrPSc from sick brain. Our findings suggest that urine is a possible source of prion transmission. Since urine produced by animals potentially infected with prions is permanently released and likely concentrated in environmental samples, such as soil and grass, this route may prove very relevant for spreading of TSEs [Transmissible Spongiform Encephalopathies] in wild and captive animals such as cervids, sheep and cattle. It is known that PrPSc is highly resistant to degradation, and infectivity can survive in the environment for a long time. Recent studies have shown that PrPSc adsorbs efficiently into soil, where it remains infectious, and that both infectivity and PrPSc can stay intact in soil for long periods. Contamination of soil with urinary prions may contribute to spreading prion disease among animals, which are known to ingest large amounts of soil, including cattle, sheep and cervids. Worrisomely, the continuous excretion of urine and the extremely high resistance of prions may lead to a progressive accumulation of infectious material in the environment, with potentially catastrophic consequences in the future.

“One of the top priorities in the prion field is to minimize further spreading of TSEs to humans or animals by limiting the exposure to contaminated material. This is a difficult problem, because prion diseases have a long clinically-silent incubation period in which infected individuals may unknowingly transmit the disease. In addition, it is possible that many individuals may remain as sub-clinical carriers during their entire life, constituting a permanent source of prions. Therefore, the development and validation of procedures to detect even the tiniest quantities of infectious material is of paramount importance.

Implementation of a large scale program to screen animals at risk of infection and diagnosis of the human population requires detection of prions in easily accessible samples, such as blood or urine. Our results showing that PrPSc can be detected in urine of a large proportion of infected animals provide a promising avenue for a sensitive and non-invasive biochemical diagnosis of prion diseases. Adaptation of PMCA [protein misfolding cyclic amplification] for detection of prions in urine of naturally infected animals and humans may offer a great possibility for routine testing of prion infections.”

By Gonzalez-Romero D, Barria MA, Leon P, Morales R, Soto C. At The George
and Cynthia Mitchell Center for Neurodegenerative diseases, Departments of
Neurology, Neuroscience and Cell Biology and Biochemistry and Molecular
Biology, University of Texas Medical Branch, 301 University Boulevard,
Galveston, TX 77555-0646, USA.

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