In a state that leads the nation in both the sheep and goat industries and in the production of wool and mohair, eradication of Scrapie continues to be a priority for 7,000 sheep producers and a growing number of goat producers.
Since 2009, there have been no confirmed cases of Scrapie in Texas. The last big spike in was in 2006 with 9 infected herds. But while Scrapie numbers have been falling in the Texas sheep industry as a result of animal identification requirements, potential for Scrapie among the state’s goat population remains a greater concern.
Nationally, in 2005, there was a peak in Scrapie numbers in goats. In the last fiscal year, for the first time ever, there were more Scrapie field cases in goats than in sheep. In fiscal years 2008 and 2011, two significant Scrapie outbreaks occurred in goats involving a total of 18 positive goats nationwide.
The concern for Scrapie in goat herds has prompted USDA to consider a proposed rule that would make the identification requirements for goats similar to those currently in place for sheep, as well as possibly expanding surveillance efforts for Scrapie in goats.
According to USDA regulations, Texas must conduct adequate Scrapie surveillance in sheep by a collecting a minimum of 598 samples annually. In 2012 there were 1,050 samples collected from sheep with Texas tags.
"Texas has made significant progress in battling this disease. The Scrapie Program has proven to be successful in Texas. Fighting this disease and implementing an animal identification program has worked," reports Dr. Dee Ellis, State Veterinarian and Director of the Texas Animal Health Commission (TAHC).
Ellis says the TAHC will continue to work with the USDA and the Texas sheep and goat industries toward the eradication of Scrapie. He says a common goal is to completely eradicate Scrapie from the United States by the year 2017, thereby qualifying the U.S. to be declared “Scrapie free,” a designation mandated by the World Organization for Animal Health (OIE). The designation could help boost the total value of U.S. sheep and goat products.
The National Scrapie Eradication Program continued to make excellent progress in fiscal year 2012. In FY 2012, the percent of cull sheep found positive at slaughter had decreased. This measure of prevalence decreased 96.2 percent since slaughter surveillance started in FY 2003, and 24.7 percent, respectively since FY 2011. Additionally, there was a 47 percent decrease in the number of infected and source flocks identified during FY 2012 compared to the previous fiscal year.
Ellis says this represents substantial progress toward the goal of becoming “Scrapie-free,” but TAHC and USDA report that animal identification tag requirements for goats would further advance the objective.
In 2001, USDA/APHIS implemented the accelerated National Scrapie Eradication Program to eliminate Scrapie from the nation's sheep flocks. The goals of the accelerated eradication program include the following:
- Eliminate outbreaks of Scrapie by 2010;
- Attain Scrapie-free status by 2017;
- To minimize ongoing losses to the sheep industry;
- To make small ruminants more competitive in the global market; and
- To mitigate impacts on international trade of all ruminant products
Enactment of the National Scrapie Eradication Program for sheep was another important step to improving the viability and sustainability of the industry.
Scrapie is a degenerative disease of the nervous system that falls into the category of Transmissible Spongiform Encephalopathies (TSE). The disease is caused by a transmissible prion or abnormal protein which is very stable in the environment. Traditional blood tests are not reliable to diagnose Scrapie, so a tissue sample is needed to diagnose it. Currently, no treatment exists for Scrapie. There is no known evidence of Scrapie transmission to humans.
While animals of any age may be exposed to Scrapie, lambs and kids are at the greatest risk of contracting the disease and are often infected by their dams shortly after birth. Typically, infected animals don't show signs of Scrapie, such as behavioral changes, tremors, and lack of coordination that progresses to recumbency and death, until they are two years of age or older.
The most effective method of Scrapie prevention is to maintain a closed flock. Raising replacement ewes, purchasing genetically resistant (RR) rams or buying from a certified-free Scrapie flock are other options to reduce the risk. At this time the resistant genetic markers in goats have not been identified; therefore, it is important to maintain sheep and goat herds separately.
Since the incubation period for Scrapie is typically two to five years, producers should record individual identification numbers and the seller's premises identification number on purchase and sales records. These records must be maintained for a minimum of five years.
"The success of the Scrapie Eradication Program is tied to producers keeping good records of sales and purchases," added Ellis.