Prions, the pathogens that cause scrapie in sheep, can survive in the ground for several years, as researchers have discovered. Animals can become infected through contaminated pastures.
Scrapie is an infectious disease in which prions destroy the animal’s brain, rather like BSE. The brain becomes porous, the sheep lose their orientation, they suffer from strong itching sensations and scrape off their fleece. Eventually, the infected animals die.
Researchers mixed the scrapie pathogens into the soil and found that after 29 months, in other words more than two years, they were still able to detect prions in the soil. In fact, the soil seems to increase the infectiousness of the pathogens. The incubation period – the time it takes for the disease to break out – is exceedingly short even after the prions have persisted in the soil for 29 months. All of the animals that were given contaminated soil became sick within a very short time. These results indicate that fresh incidences of scrapie among sheep are due to contaminated pastures.
It is not yet known whether the pathogens that cause BSE and CWD are equally resistant as these scrapie pathogens.
Source: EurekAlert, 11 August 2008
Chapter: Animals & Insects :: 2 September 2008
