Scrapie reduction unlikely without effective breeding programme
Over the last ten years Classical scrapie in sheep has decreased in countries where breeding programmes for resistance were effectively implemented, say EFSA experts.
EFSA has assessed the state of scrapie in the EU since the introduction ten years ago of a series of measures to monitor and control the disease. Scrapie is a fatal disease that affects sheep and goats. It belongs to the same family of diseases as bovine spongiform encephalopathy (BSE) which is found in cattle and is commonly known as mad cow disease. There is no evidence that scrapie has ever been transmitted to humans. The infectious agent is thought to be an abnormal form of a protein, also called a prion.
Experts of EFSA’s Panel on Biological Hazards have concluded that an eradication policy that relies only on the detection and culling of infected flocks and does not include breeding programmes for resistance is unlikely to succeed. This is both because of the characteristics of this disease and because the classical scrapie agent can persist in the environment for years.
“Sheep with a particular genetic makeup are resistant to Classical scrapie and breeding choices allow an increase in the flock’s resistance to the disease” explains Giuseppe Ru, Chair of EFSA’s Working Group on scrapie situation in the EU.
EFSA experts concluded that Classical scrapie in sheep may die out if the percentage of resistant sheep is above a certain threshold.
Occurrence of Classical scrapie varies greatly across the EU and its evolution over time should be considered country-by-country. Overall, it has been reported in 17 Member States; in some of them cases have decreased over time, while in others no clear trend was observed.
EFSA experts recommend strengthening surveillance activities to detect infected flocks and control the disease, increasing the implementation of breeding programmes for resistance in sheep and starting their use in goats too.
- Scrapie comes in two variants. Classical scrapie is transmitted through exposure to scrapie-infected animals (e.g. via milk or placentae) and their environment. Scientific evidence suggests that Atypical scrapie, the second variant, is spontaneous and non-contagious. In this opinion EFSA experts have considered both variants, with a particular focus on Classical scrapie.