Risk Assessments

Risk assessments (RA) support managed movement and permitting of animals and animal products during disease outbreaks.

A quantitative risk assessment was published in 2023 by Meyer, Weiker, and Meyer that described mitigation steps for the release of FMD virus in frozen semen collected from infected, undetected bulls using data from five of the largest U.S. production centers. Probability and incidence data were modeled since the U.S. has been free of FMD since 1929. Several pathways were considered in their model including:

  1. Semen collected during an outbreak at the facility
  2. Failure to detect FMD in donor bulls through clinical surveillance
  3. Failure to detect FMD in donor bulls while frozen semen stored either 14 or 30 days
  4. Infected donor bull has semen collected and semen has viable FMD virus
  5. Failure to detect FMD virus in semen via quality control and RT-PCR testing
  6. Failure to detect FMD antibody or antigen on routine blood test

The mitigation step that was most effective at reducing the risk of FMD release was serum antibody testing performed every two weeks (model test sensitivity of 92-100%, specificity of 97%). That step combined with holding semen for 14 or 30 days had a median annual probability of release of at least one FMD contaminated batch of semen from the five facilities of less than one in 100 billion. (Source: Meyer A, Weiker J, Meyer R. Laboratory testing and on-site storage are successful at mitigating the risk of release of foot-and-mouth disease virus via production of bull semen in the USA. PLoS ONE 18(11): e0294036;2023.)

While there is no validated test for semen as of May 2024, nor is it an approved sample type, the U.S. has a commercially available and validated antibody enzyme linked immunosorbent assay (ELISA) for FMD. Additionally, active observational surveillance would mitigate two of the pathways above. Enhanced biosecurity for FMD could mitigate the introduction of the virus. Read the full Bovine Germplasm Movement Plan guidance for additional details. An overview is available in the Executive Summary.

There are no risk assessments underway for live cattle movements (as of May 2024).