Brain-destroying prion disease can spread among deer through faeces shed by animals which have been infected by the deadly pathogen but are not sick, a study published on Wednesday suggests.
Brain-destroying prion disease can spread among deer through faeces shed by animals which have been infected by the deadly pathogen but are not sick, a study published on Wednesday suggests.
The paper implies that the mysterious disorders known as chronic wasting disease (CWD) and scrapie -- cousins of mad-cow disease -- could be transmitted in a hitherto-overlooked way, posing a headache for farmers.
Research Says Gene Mutation Alone Causes Transmissible Prion Disease
Mutations associated with prion diseases are sufficient to cause a transmissible neurodegenerative disease, according to Whitehead researchers.
Mutations associated with prion diseases are sufficient to cause a transmissible neurodegenerative disease, according to Whitehead researchers.
Prion diseases are well-researched disorders in deer (CWD), cattle (bovine spongiform encephalopathy, or BSE), sheep and goats (scrapie), cats (feline spongiform encephalopathy, FSE) and in humans (Creutzfeldt-Jakob disease, CJD).
Many aspects about them are unclear, though. In deer, CWD is known to be handed on from mother to offspring, but other paths of infection are deemed possible.
Scientists Uncover Genetic Mutation That can Cause Mad Cow Disease
While mad cow disease has been thought to be a foodborne disease for years, a new study has shown that a genetic mutation also causes it.
While mad cow disease has been thought to be a foodborne disease for years, a new study has shown that a genetic mutation also causes it.
Over the course of months, the investigators collected the faeces of five mule deer (Odocoileus hemionus) and then orally infected them with CWD prions.
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Mad Cow Disease Transmitted Through Farmed Fish Too
Farmed fish, if fed by-products rendered from cows, could transmit Creutzfeldt Jakob disease-commonly known as mad cow disease.
Farmed fish, if fed by-products rendered from cows, could transmit Creutzfeldt Jakob disease-commonly known as mad cow disease.
Faecal samples -- irradiated to kill germs and viruses but leave the prions untouched -- were injected into the brains of genetically modified mice.
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But 14 out of 15 samples that were collected after the four-month mark caused the mice to fall sick with CWD-like symptoms.
The results, say the authors, point to a "horizontal" way by which CWD could spread among deer in the wild -- and, possibly, by which scrapie could spread among sheep and goats.
The "faecal-oral route" was given credence by a 1994 Icelandic study in which sheep with scrapie were held in a field, removed and then replaced with scrapie-free sheep, which then went on to develop the disease.
But an unresolved question is whether prions can survive long enough in the soil to infect other animals. Past studies have sent back conflicting data on this; some say harsh weather and microbial enzymes in the soil degrade the pathogen.
The new paper did not touch on BSE. That disease, which erupted in Britain in the 1980s, unleashed a scare in 1996 when BSE-infected beef was linked to a rare form of fatal neurodegenerative disorder in humans, variant CJD.
The causes of BSE have been fiercely debated. One idea is that herds became infected by eating the ground-up carcasses of scrapie-infected sheep.
BSE has been fought through a culling of animals and a change of feeding practices. Several studies into cattle suggest there is no "faecal-oral route" for BSE.
Source-AFP
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