Grad Student Competition
A quantitative model of the risk of FMD transmission following cattle movements during an outbreak
| Date/Time: |
9/12/2025
09:30
|
| Author: |
Torre Dunlea |
| Clinic: |
Kansas State University |
| City, State, ZIP: |
Manhattan, KS 66506 |
T. Dunlea, MS
1
;
A. Kerns , BS
2
;
S. Yadav, DVM, PhD
1
;
M. Sanderson, DVM, MS
1
;
1Center for Outcomes Research and Epidemiology, Department of Diagnostic Medicine & Pathobiology, College of Veterinary Medicine. Manhattan, Kansas 66506
2Department of Statistics, Kansas State University. Manhattan, Kansas 66506
Introduction:
Foot and Mouth Disease (FMD) presents a major economic threat to the U.S. cattle industry. A key pathway for FMD transmission between farms is through direct contact, primarily driven by the movement of livestock between operations. While the Secure Beef Supply (SBS) project offers guidelines to control the spread of infection—including movement controls, biosecurity protocols, and daily active observational surveillance (AOS)— there has been no quantitative assessment of FMD transmission risk under the current SBS recommendations. Additionally, there is significant concern that overly restrictive movement control measures could severely disrupt business continuity. Therefore, the quantitative estimation of outbreak management strategy effectiveness is imperative. This study addresses this gap by estimating the transmission risk associated with cattle movements during an FMD outbreak.
Materials and methods:
Simulations from InterSpread Plus (ISP, a spatially explicit, stochastic FMD spread model) were used to estimate local, indirect, and direct daily incidence risk for cattle farms within 200 km of an infected premises (IP). The effect of biosecurity on incidence risk was modeled for farms intending to transport livestock (movement farms). For infected movement farms, the within-herd disease dynamics and AOS processes were used to estimate the probability of detecting infection before the day of intended shipment. Movement farms were categorized as uninfected, infected but not detected, or infected and detected. Risk resulting from shipment from an infected but undetected farm to another farm or auction market were estimated. For auction market shipments, the number of infected sale lots was estimated from consignment lot sorting, mixing, and transmission within the auction market.
Results:
Local transmission was predominant for movement farms within 3 km of an infected premises (IP), with infection risk decreasing sharply as distance increased. Additionally, increasing the number of direct cattle shipments received increased the infection risk for the movement farm. Movement farm biosecurity reduced infection probability, however, farms within 3 km of an IP still faced substantial risk even at the highest level of biosecurity. For farms situated more than 3 km from an IP, baseline infection risk was much lower. Allowing movements from farms more distant from an IP could help maintain business continuity at a lower risk to both other farms and auction markets. Shipment of cattle from infected but undetected farms to auction markets resulted in increased number of infected sale lots, predominantly due to sorting and mixing.
Significance:
In response to an FMD outbreak, prompt and focused disease control programs will be necessary for disease eradication. However, overly restrictive controls can impede business continuity. Quantitative assessment of cattle movement risk based on the risk of herd infection and probability of detection prior to movement can help to estimate the risk distribution of specific cattle movements. The results from this study will improve our ability to make safe, informed cattle movement decisions, minimizing the impact of an FMD outbreak as well as mitigating business continuity impacts on the cattle industry.
