The present risk assessment proactively evaluated the risk of infecting susceptible livestock by
the movement of Foot and Mouth Disease (FMD) infected carcasses (swine and cattle) from
FMD infected premises. The risk assessment evaluated the most up to date available science and
solicited opinion from experts when data was lacking. This risk assessment is proactive in nature
and the scenarios, pathways and depopulation practices assessed were based on the current
practices and regulations applicable during an animal disease outbreak in the US. The
characteristics, types of conveyance methods, and equipment used to transport the infected
carcasses were provided from expert opinion and verified through site visits. Different modeling
techniques were used to estimate the number of infected animals during a FMD outbreak at
various time intervals, the total time estimated from infection to depopulation and the total
amount of FMD virus (FMDv) contained in a disposal truck. The main outcomes of the risk
assessment should be reviewed if needed as new data becomes available in the future.
Risk estimation: The risk of FMD infection of susceptible livestock associated with the
movement of swine and cattle carcasses from FMD infected premises to a disposal site during a
FMD outbreak in the United States is negligible when using a standard rendering truck (tailgate
sealed and tarp cover) and a Bio-Zip bag, and between negligible and low when using a
standard rendering truck or a roll-off /dump truck with a Bio-Zip bag. The risk level in other
scenarios (uncovered standard rendering trucks, uncovered roll-off/dump trucks, covered rolloff/
dump trucks and a liner) is between moderate and high.
Main results: Time for FMD detection was estimated by a disease spread model to be between
4-10 days for swine and beef cattle and 3-9 days for dairy cattle premises of different sizes. Total
time from infection to depopulation (including detection and confirmation) for the first FMD
infected case was estimated to be between 10-15 days for swine, 8-12 days for dairy and 10-14
days for beef cattle premises. Total time estimated for subsequent FMD cases was between 7-12
days for swine, 6-9 for dairy and 8-11 days for beef cattle premises. Most of the animals (>65%
for the first case and >81% for subsequent cases) were viremic at the time of depopulation. The
average concentration of FMDv in a carcass in experimental inoculation studies was 103 Plaque-
Forming Unit per gram (PFU/g) for a pig carcass and 106 PFU/g for a cattle carcass. The total
amount of infected carcasses moved to the disposal site (relative to the size of the animal carcass
and the capacity of the truck trailer) was between 23-390 cattle carcasses and 117-780 pig
carcasses per truck. Any small amount of body fluids (1 mL) would contain virus that is equal
and greatly exceeds the infective dose by oral and inhalation route for pigs and cattle. The
likelihood that swine and cattle carcasses moved from FMD positive premises will contain an
infective dose was high. The use of a Bio-Zip bag in a standard rendering truck (tailgate sealed
and tarp cover) reduces the likelihood of leakage, spillage and aerosolization to negligible.
This project was developed in funded through a sub-award with West Texas A&M University through USDA-APHIS and DHS.
Slingluff, Jamie; Sampedro, Fernando; Goldsmith, Timothy J..
Risk Assessment for the Transmission of Foot and Mouth Disease via Movement of Swine and Cattle Carcasses from FMD-infected Premises to a Disposal Site.
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