Transmissible Spongiform Encephalopathy (TSE)
Introduction
Transmissible Spongiform Encephalopathies (TSEs) are infectious diseases of the brain caused by altered prion proteins. These altered Prions are extremely resistant to heat and chemicals. Even heating to 100°C cannot inactivate prions adequately and many of the usual disinfectants have hardly any effect at all. Furthermore, Prions are also very difficult to decompose biologically – in soil they survive for many years.
Prion diseases occur both in animals and humans and are transmissible between species:
- Humans: CJD (Creutzfeldt Jakob Disease) or GSS (Gerstmann Sträussler Syndrome)
- Cattle: BSE (Bovine Spongiform Encephalopathy)
- Sheep and Goats: Scrapie
- Deer / Elk: CWD (Chronic Wasting Disease)
The diseases cause a slow degeneration of the central nervous system, which inevitably leads to death. A very long period of time elapses between infection and the appearance of the first clinical symptoms: typically 2-4 years in sheep, 3-6 years in cattle and more than 10 years in humans. As a general rule, once the symptoms have appeared, the disease leads to death within only a few months. The diseases occur world-wide, but the highest prevalence of BSE is in Europe, whereas CWD is most commonly found in North America.
Human health risk
Like other TSEs, vCJD transmission can occur via several routes:
From animals to humans:
FOOD
The primary risk of humans developing the new variant form of Creutzfeldt-Jakob Disease (vCJD) is through eating BSE-contaminated food products.
The European Union has instituted a series of measures to minimize the risk of disease transmission both among animals and from animals to humans, including:
- A testing program for the identification and elimination of BSE-infected animals: A study carried out by Prionics in 1998 using its BSE test showed for the first time that BSE can enter the food chain. Subsequent studies underlined these findings and led to the institution of compulsory rapid post mortem testing of slaughtered cattle older than 30 months.
- A ban on feeding mammalian protein to cows, sheep and goats to halt the spread of BSE.
- The removal of tissues known to harbor particularly high amounts of infectivity (specified risk materials, SRM) such as brain, spinal cord and intestines from cattle at slaughter.
Pharmaceuticals and cosmetics
For pharmaceutical products, cosmetics and other products that contain bovine proteins, raw materials are mostly sourced from BSE-free countries. However, consumers need to enquire whether or not this is the case for each particular product.
From humans to humans (Iatrogenic Transmission):
Infection may be spread via blood, transplantation, injection of human growth hormone or surgical instruments. > more
Economic impact
Major economic losses are caused by the killing and complete destruction (culling) of the cohort animals linked to a positive BSE case as is regulated by the current European Union legislation on TSEs. Also, the costs associated with the removal and destruction of Specified Risk Material (SRM) from cattle, sheep and goats has had a considerable economic impact. Furthermore, export restrictions from affected areas will have a negative impact on the meat industry.
Diagnostic solution
The Prionics®-Check test family offers TSE rapid tests for different kinds of TSEs:
All tests are based on a single sample-preparation procedure and are therefore fully compatible. The Prionics®-Check tests are extremely suitable for routine analysis of large sample numbers and are absolutely reliable, even under rough, high-throughput conditions. Furthermore, our Prionics®-Check tests are the most frequently used TSE tests in the world, and this technology has been implemented in over 30 national reference laboratories around the world.
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Prionics®-Check tests allowed for CWD testing in the EU.
EC Decision on a survey for chronic wasting disease in cervids, March 19, 2007
