12/14/2024
HAS SCRAPIE BEEN ERADICATED?
Susan Schoenian
Sheep & Goat Specialist Emeritus
University of Maryland Extension
Almost, but not quite. The last case of “classical” scrapie in the US was found in 2021. As of 2024, 47 states have not had a case of scrapie (or a traceback in sheep) for more than 7 years.
If we do not have another case of scrapie by 2028, the US will officially and finally be declared free from scrapie. Only Australia and New Zealand currently enjoy this status.
It has been a long road. While scrapie has been recognized as a disease in England and Europe for more than 250 years, the first case of scrapie (in a sheep) in the US wasn’t until 1947. The first goat was diagnosed in 1969.
In 2002, scrapie reached an all-time high in the US, when approximately 1 in 500 sheep were infected with the disease. Scrapie has never been as common in goats, but goats are essential to eradication.
Scrapie is a fatal, degenerative disease that affects the central nervous system of sheep and goats. It is among several diseases classified as transmissible spongiform encephalopathies (TSEs).
TSEs became the subject of increased attention and concern when mad cow disease (BSE) was discovered in England in 1986, and it was hypothesized that TSEs were jumping species.
While scrapie is primarily a disease of older sheep/goats (over 2), animals usually get infected when they are very young (from mother to offspring) via contact with infected birth fluids, placenta, and milk.
Due to its long incubation period, scrapie is difficult to diagnose. Brain or lymphoid tissue is needed for testing.
The economic impact of scrapie in the US is estimated at $10-20 million per year, the result of lost production, lost exports, and increased production and disposal costs. In 1952, the National Scrapie Eradication Program went into effect. It was revised in 2001 to accelerate the eradication of scrapie from the United States.
Since 2001, there has been mandatory identification (with official scrapie ID; for traceback) of most sheep and goats, along with record keeping requirements. Genotypes having natural resistance to scrapie have been identified and used to select resistant stock.
An important part of the eradication efforts has been slaughter surveillance. Since 2003, 745,540 sheep and goats (mostly culls) have been tested for scrapie. All these efforts reduced the incidence of scrapie (in sheep) to 0.0% in 2020, and as previously stated no new cases since 2021.
To get the US sheep/goat industry to the finish line of eradicating scrapie, it is essential that every producer continue to do their part by identifying their animals (when they leave the home farm) and reporting any scrapie-suspect animals to their veterinarian or other animal health authority.
Scrapie symptoms include progressive weight loss, incoordination, gait and behavior abnormalities, and intense itching (rubbing).
Another way to help the efforts is to submit heads (of mature animals) for (free) scrapie testing, especially if the deceased animal died of unknown causes or displayed neurological symptoms before death.
Originally published in the Delmarva Farmer, December 2024