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

Nicolas C. Cardenas, Jacqueline Marques de Oliveira, Andre de Medeiros C. Lins, Fernando Endrigo Ramos Garcia, Marcus Vinicius Angelo, Robson Campos dos Anjos, Fabricio de Lima Weber, Frederico Bittencourt Fernandes Maia, Vanessa Felipe de Souza, Gustavo Machado

TL;DR

It is 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).

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.

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

TL;DR

It is 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).

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.
Paper Structure (23 sections, 4 figures, 4 tables)

This paper contains 23 sections, 4 figures, 4 tables.

Table of Contents

  1. Introduction
  2. Methodology
  3. Results
  4. Discussion
  5. Conclusion
  6. Acknowledgments
  7. Funding statement
  8. Data Availability Statement

Figures (4)

  • Figure 1: Farm density represented in a 10 km$^2$ hexagon grid. The hexagon intensity color represents the number of farms allocated; note that the color scale is log10. White lines represent the municipality's division of the state of Mato Grosso do Sul, Brazil.
  • Figure 2: Initial conditions. Distribution of secondary infected farms used in the scenarios for the control strategies section of the model. Color represents the presence of at least one species per farm. For mixed-species farms, classification is hierarchical based on the highest-risk species present (bovine > small ruminants > Swine).
  • Figure 3: Distribution of the total vaccinated bovines. The y-axis denotes the number of vaccinated bovines, while the x-axis represents simulated scenarios. The dots and shaded area represent the distribution of individual simulations.
  • Figure 4: Distribution of number of depopulated animals. The y-axis denotes the number of depopulated animals, while the x-axis represents simulated scenarios. The dots and shaded area represent the distribution of individual simulations.