A Modelling Assessment of the Impact of Control Measures on Simulated Foot-and-Mouth Disease Spread in Mato Grosso do Sul, Brazil

Abstract

This study simulated the introduction of Foot-and-mouth disease (FMD) into Mato Grosso do Sul, Brazil, to evaluate the effectiveness of outbreak control strategies. Our susceptible-exposed-infected-recovered model generated a range of outbreak sizes across the state. These outbreaks were used to model control actions across six scenarios: high vaccination, two variations of moderate depopulation combined with vaccination, high depopulation with limited vaccination, and moderate and high depopulation alone. Our results showed that relying solely on high vaccination was the least effective approach; it controlled only 2.22 % of outbreaks and resulted in the highest number of infected farms and the longest control duration. Mixed strategies, busing, moderate depopulation, and vaccination controlled approximately 91 % of outbreaks. The use of moderate depopulation alone controlled 96.60 % of outbreaks, and it was 14-15 days faster than the mixed approaches. The most effective strategy combined the highest depopulation capacity with limited vaccination, controlling 100 % of outbreaks and producing the shortest control duration. The number of vaccinated animals ranged from 211,002 under the optimal strategy to 596,530 when the control strategy included only vaccination. We demonstrated that vaccination alone was insufficient to eliminate outbreaks, and that depopulation and vaccination strategies would be required to stamp out future FMD introduction in Mato Grosso do Sul (MS). The success of such a strategy would eliminate between 90 % to 100 % of outbreaks in 10 to 15 days and reduce the number of infected farms by 10 to 13.