Use of animal movement data and epidemiological modeling to identify premises at high risk of infection in the event of a foot-and-mouth disease epidemic

Foot and mouth disease (FMD) is one of the most contagious and economically relevant diseases affecting livestock and is rapidly transmitted between hosts. Fortunately, the US swine industry has not experienced an FMD epidemic for almost a century. However, the recent introduction of pathogens, such as PED, demonstrate the need for increasing the industry’s ability to early respond and efficiently mitigate the potential impact of introductions of devastating diseases, such as FMD. Here, disease transmission models have been used to predict the spread of FMD virus and evaluate the impact of control strategies.

The objective of this project was to combine measureable information on FMD virus transmission into a disease model to measure the impact of movement data on the spread of FMD within a production system in the US to capture both within-herd and between-herd transmission. We aim to use these data to develop control strategies that incorporate currently accepted OIE containment strategies (i.e. movement bans, culling, and vaccination) and tailored control strategies based on characteristics of farms that may increase their risk of infection (i.e. number of shipments of animals received). The results of this study show that:

• Containment strategies significantly influence the predicted number of farms infected during an epidemic, as well as the mean duration of the epidemic. By increasing the radius of the control zones by 20% and 50%, we see a significant reduction in the predicted mean number of farms infected during an epidemic, as well as the mean duration of the epidemic.

• Moreover, FMD persistence within a population was dependent on farm structure and proportion of individuals in the population capable of becoming infected as seen in the modeled farrow to finish and farrow to wean herds, which are both birthing disease vulnerable piglets on a weekly basis.

• For those reasons, making the simplifying assumptions about how pigs contact each other on a farm may be sufficient to model FMD spread when aiming to measure average values of infection in the population. However, farm structure and demography needs to be considered to accurately model more detailed aspects of FMD infection in the herds.