- Top publications | May
- Jason A. Galvis et al.
Accounting for multiple modes of livestock disease dissemination in epidemiological models remains a challenge. Here we developed and calibrated a mathematical model for transmission of porcine reproductive and respiratory syndrome virus (PRRSV), tailored to fit nine modes of between-farm transmission pathways including: farm-to-farm proximity (local transmission), contact network of batches of pigs transferred between farms (pig movements), four different contact networks of transportation vehicles (vehicles to transport pigs to farms, pigs to markets, feed and crew), the amount of animal byproducts within feed ingredients (e.g. fat and meat and bone), and finally we also accounted for re-break probabilities for farms with previous PRRSV outbreaks. The model was calibrated on weekly PRRSV outbreaks data. We assessed the role of each transmission pathway considering the dynamics of specific types of production (i.e., sow farm, nursery). Our results estimated that the networks formed by transportation vehicles were more densely connected than the network of pigs transported between-farms. The model estimated that pig movements and farm proximity were the main PRRSV transmission routes regardless of farm types, but vehicles transporting pigs to farms explained a large proportion of infections, sow = 20.9%; nursery = 15%; and finisher = 20.6%. The animal by-products showed a limited association with PRRSV outbreaks through descriptive analysis, while our model results showed that the contribution of fat and meat and bone was 2.5% and 0.03%, respectively, of the infected sow farms.