Foot-and-Mouth Disease in Bolivia: Simulation-Based Assessment of Control Strategies and Vaccination Requirements

Examining the dissemination dynamics of foot-and-mouth disease (FMD) is critical for revising national response plans. We developed a stochastic susceptible-exposed-infected-recovered (SEIR) metapopulation model to simulate FMD outbreaks in Bolivia and explore how the national response plan impacts the dissemination among all susceptible species. We explored variations in the control strategies, mapped high-risk areas, and estimated the number of vaccinated animals during the reactive ring vaccination. Initial outbreaks ranged from 1 to 357 infected farms, with control measures implemented for up to 100 days, including control zones, a 30-day movement ban, depopulation, and ring vaccination. Combining vaccination (50-90 farms/day) and depopulation (1-2 farms/day) controlled 60.3% of outbreaks, while similar vaccination but higher depopulation rates (3-5 farms/day) controlled 62.9% and eliminated outbreaks 9 days faster. Utilizing depopulation alone controlled 56.76% of outbreaks, but had a significantly longer median duration of 63 days. Combining vaccination (25-45 farms/day) and depopulation (6-7 farms/day) was the most effective approach, eliminating all outbreaks within a median of 3 days (with a maximum of 79 days). Vaccination alone controlled only 0.6% of outbreaks and had a median duration of 98 days. Ultimately, results showed that the most effective strategy involved ring vaccination combined with depopulation, requiring a median of 925,338 animals to be vaccinated. Outbreaks were most frequent in high-density farming areas, such as Potosí, Cochabamba, and La Paz. Our results suggest that emergency ring vaccination alone cannot eliminate FMD if reintroduced in Bolivia, and combining depopulation with vaccination significantly shortens the outbreak duration. These findings provide valuable insights to inform Bolivia's national FMD response plan, including vaccine requirements and the role of depopulation in controlling outbreaks.