Friday, April 11, 2008

Nor98-like scrapie found in U.S.

Nor98 is an atypical scrapie first found in Norway in 1998. It has since been found in sheep and goats in many European countries. Last year, the first case of Nor98 was found in the United States. Since then four more cases have been discovered; none in goats.

Nor98 affects sheep and goats of all common genotypes, including those that are resistant to classical scrapie. Nor98 is more difficult to detect than classical scrapie because the distribution of prions is different, and live animal tests involving the lymph tissue do not work.

Unlike classical scrapie, most cases of Nor98 occur in normal-appearing sheep that are over five years of age. Twenty-five pecent of the cases occur in sheep over 10. Seldom does the disease occur in more than one sheep in a flock (unless flock size exceeds 500). There is speculation that Nor98 may be a sporadic disease of sheep, occurring primarily, but not exclusively in older sheep.

The international community is still deciding how to deal with Nor98 scrapie. Research is currently underway in Europe and the United States. At this point, it is not known if and how Nor98 is transmitted. Age and genetics are considered primary risk factors.

To prevent the introduction of all types of scrapie, sheep and goat producers should maintain closed flocks. Breeding stock should only be purchased from farms with a known scrapie status. The genetics of purchased animals should be known.

The goal of the American Sheep Industry Association (ASI) and U.S. sheep and goat industry is to eradicate scrapie by 2010 and to have the World Organization for Animal Health declare the United States scrapie-free by 2017.

Read about Nor98 in the March 2008 issue of Scrapie: Eradicate it