Scrapie

The National Scrapie Eradication Program (NSEP), a cooperative State-Federal-industry program, is working to eradicate classical scrapie from the United States and meet World Organisation for Animal Health (WOAH) criteria for disease freedom. To date, the program has eliminated scrapie in 99 percent of U.S. sheep and goats. The program is conducting targeted sampling of subpopulations that have a higher prevalence of scrapie than the general sheep/goat population to find the remaining cases.

• NSEP Standards
• NSEP Annual Report -  FY 2023
  • NSEP Quarterly Report - June 2024

Modernizing NSEP

APHIS published a final rule in the Federal Register in 2019, updating scrapie program regulations (9 CFR 79). The rule established a more flexible approach to disease investigations and affected flock management and more consistent animal identification and recordkeeping requirements for sheep and goats. The rule also moved specific requirements for official eartags and official identification methods, such as tattoos and implantable electronic ID (microchips), and indemnity calculations to the NSEP Standards.

The NSEP surveys for scrapie in the United States. Surveillance components include:

1. Regulatory scrapie slaughter surveillance
2. Non-slaughter surveillance (for example, trace investigations, on-farm testing)
3. The Scrapie Free Flock Certification Program

Since 2002, the prevalence of scrapie has decreased significantly through existing eradication efforts. This is largely due to effective slaughter surveillance of geographically distributed sampling based on annual population estimates. However, to declare the United States “scrapie free,” we must prove to the world that we have conducted testing in all sheep and goat populations. That is why owner submission of samples from sheep/goats over 18 months of age found dead or euthanized on farm is extremely important. With the help of those who raise sheep and goats, APHIS will be able to declare the U.S. free of scrapie. Scrapie currently costs sheep and goat industries approximately $10 to $20 million in lost export opportunities, annually.

• National Scrapie Surveillance Plan (revised August 2022)
• Scrapie Incentive Program
• FY 2024 State Sheep and Goat Sampling Minimums

Producers, accredited veterinarians, APHIS representatives, and State animal health employees may collect and submit samples from adult sheep or goats. APHIS provides shipping boxes and pre-printed, postage-paid labels at no cost to producers and accredited veterinarians. APHIS will pay for scrapie testing of up to 30 animals per flock per year. Producers may remove and submit whole heads or report deceased sheep or goats and ask for help with submitting samples. Accredited veterinarians can either remove and submit whole heads or collect and submit specified tissues.

To request a box, or for more guidance on collecting and submitting samples, contact the APHIS Area Veterinarian in Charge in your State or your State's designated scrapie epidemiologist (DSE). 

Shipping Instructions

Whole head samples
Ship the cooler containing the head with frozen cold packs overnight to Remington Locker, APHIS' sample collection facility:

18795 S 580 W 
Remington, IN 47977 
Phone: 317-347-3100 
Fax: 219-261-2357 
Email: remington.locker@usda.gov

Be sure to inform the facility of the shipment’s delivery date.

Tissue samples
Ship tissue samples to an APHIS-contract laboratory.

Contact the APHIS Area Veterinarian in Charge in your State for Instructions

Test Results
Positive test results will be confirmed by the National Veterinary Services Laboratories (NVSL) or an NVSL-approved laboratory.

In 2021, APHIS started using a new indemnity process and published the VS Indemnity Table, which  supersede section II.J. 4. (a) of the Program Standards that details how sheep and goat indemnity values are calculated.

Approximately 30 percent of U.S. sheep are genetically susceptible to scrapie. Some animals have been bred to be genetically resistant to the disease. Because scrapie persists in the environment for years, owners of previously infected flocks should restock with rams that are resistant and ewes of resistant or less susceptible genotypes. 

All goat breeds are susceptible to scrapie. Three goat prion gene alleles have now been shown to confer meaningful resistance to classical scrapie. They are S146 or D146 (serine [S] or aspartate [D] amino acid at prion protein position 146), and K222 (lysine [K] at position 222). Goats bearing a single copy of one of these alleles are much less susceptible to infection during natural outbreaks as well as direct challenge experiments.  It is believed that goats that are homozygous for these alleles may be highly resistant but there are so few of these goats that it hasn’t been demonstrated. For regulatory purposed all exposed goats are currently treated as susceptible; however, APHIS may conduct genetic based pilot projects like what was done with sheep if infected goat herds with suitable genetics are found. Goat genetic susceptibility testing is now available at an approved laboratory.

Major Codons Associated With Scrapie in Sheep

Codon 171 is the major determinant of classical scrapie susceptibility in the United States. It plays a role in sheep susceptibility to the major type of classical scrapie found in the United States, valine-independent scrapie.

• It codes for the amino acids Glutamine (Q), Arginine (R), Histidine (H) or, rarely, Lysine (K).
• Q is associated with increased susceptibility to classical scrapie, while R is associated with increased resistance.
  • H is considered to have the same susceptibility as Q. The relative susceptibility of K is still under investigation. Therefore, both H and K are reported as Q by most laboratories and are treated as Q for regulatory purposes.
  • Over 99 percent of the classical scrapie cases in the United States that have been genotyped were QQ.

Codon 136 plays a role in sheep susceptibility to the less common type of classical scrapie found in the United States, valine-dependent scrapie.

• It codes for the amino acid Alanine (A), Valine (V) or, rarely, Threonine (T).
• V is associated with increased susceptibility to classical scrapie.
• The occurrence of T is extremely rare and as of September 2012 has never been reported in the United States. Because its role in susceptibility is unknown, if it were identified in U.S. sheep it would be reported by most laboratories as V and treated as V for regulatory purposes.

Codon 154 plays a minor role in classical scrapie and is not often used in the United States as part of a breeding or regulatory strategy. It is, however, associated with increased susceptibility to Nor98-like scrapie.

Codon 141 is associated with increased susceptibility to Nor98-like scrapie. Its role in classical scrapie, if any, is unknown.

Codon 112 also plays a minor role in classical scrapie, although its association with classical scrapie resistance is still under investigation.

Testing for Genetic Susceptibility

Genotype testing for susceptibility to scrapie is a key component of NSEP. Note: Genetic testing does not tell you whether a sheep or goat is infected with scrapie.

Sample submissions must meet the following requirements for official genotype testing:

• Sheep or goats are officially identified.
• The blood is drawn by a Federal or State animal health official or an accredited veterinarian.
• The sample is submitted with a VS Form 5-29 to an APHIS-approved  goat or sheep genetic susceptibility testing laboratory.
• The sample meets any additional requirements set by the APHIS-approved lab.

Becoming an APHIS-Approved Genotyping Laboratory

Approved genotyping laboratories may conduct privately funded official scrapie genotype testing and compete for NSEP-funded official genotyping. This approval lasts for 1 year and is subject to review and renewal.

Each laboratory must apply to conduct official genotype tests. Interested labs should send an application package to the NVSL. The application must contain the following information about the laboratory:

• Laboratory name and address
• Name of the legally responsible official and, if different, the director of the laboratory
• A description of the laboratory facilities and equipment that will be used in performing genotype tests
• A list of the types of samples that will be tested
• The standard operating procedure for each test to be used, including methods, materials, equipment, and other relevant information
• A list of the names of individuals performing specific tests and a detailed statement of each individual’s qualifications
• A detailed description of the procedures to satisfy the recordkeeping requirements of the Scrapie Eradication Program
• A description of the specific procedures for reporting test results
• The laboratory quality assurance manual
• A statement authorizing APHIS to inspect the laboratory without notice during normal business hours (inspection may include, but is not limited to, reviewing and copying records, observing tests being conducted, and interviewing personnel)

After submitting a complete application package, the laboratory will have additional tasks such as completing a proficiency test panel and site visits to demonstrate technical competency and evaluate testing and laboratory protocols. Following completion of these tasks, APHIS will extend approval in writing to the laboratory. For more information, contact scrapie@usda.gov.

The National Scrapie Flock Certification Program (SFCP) increases the marketability of sheep and goats from flocks that have demonstrated freedom of scrapie disease by adhering to program standards. This is a voluntary program for producers who are committed to monitoring their flocks for clinical scrapie signs and reporting any suspect animals for testing. Participants in this program benefit by decreasing the risk of introducing classical scrapie into their flocks.

Participants may participate in one of two categories in the SCFP program:

1. Export Category—Monitors and samples participating flocks. If conditions are met, it may lead to Export Certified status and recognition of negligible scrapie risk.
2. Select Category—Test samples from mature sheep and goats to identify and remove infected flocks.

Find SFCP participants in the U.S.

How To Apply

To participate in the SCFP program in either category you must complete the SFCP application form (VS Form 5-22).

Note: The Export Category has additional documentation requirements for applying such as a flock inventory and an initial flock inspection.

For more information on this voluntary program, including how to enroll, please contact scrapie@usda.gov.