The impact of movement and vaccination on Peste des Petits Ruminants disease spread between two different agroecological zones

Abstract

Peste des Petits Ruminants (PPR) is a highly infectious and contagious viral disease that affects small ruminants. The spread of PPR varies across Ethiopia’s agroecological production systems. This study proposes a novel two-patch deterministic mathematical model to investigate the impact of small ruminant movement on the spatial spread of the PPR virus between two distinct zones, with a focus on small ruminant movement between lowland (pastoral) and highland (sedentary) agroecological zones. We establish the essential characteristics of the model, construct control reproduction numbers ($R_v$) for both isolated and coupled systems, and show that the disease-free equilibrium is locally and globally stable when $R_v<1$ and unstable when $R_v>1$. A key contribution of this research is the application of a SEIR model to empirical data from a nationwide prevalence survey of PPR in Ethiopia, enabling the estimation of critical parameters such as disease transmission levels and current vaccination coverage. Our numerical simulations reveal the interplay between small ruminates movement and vaccination strategies, offering valuable insights into their effects on PPR persistence and extinction across various scenarios. Ultimately, the findings emphasize the importance of coordinating vaccination programs for both zones with effective movement control measures to optimize disease control strategies and enhance PPR eradication efforts at national level.