A Deterministic Optimal Control Model for Peste Des Petits Ruminants in Ethiopia: Assessing the Role of Infective Recruits and Cost‐Effectiveness Strategies

ABSTRACT Peste des petits ruminants (PPR) is a highly contagious viral disease of small ruminants with substantial health and economic impacts. We develop a deterministic optimal‐control model that explicitly accounts for infection introduced via restocking and evaluates time‐dependent interventions: External biosecurity (), internal biosecurity (), vaccination of susceptibles (), and treatment of infectives (). We establish the fundamental properties of the model regarding biological feasibility and well‐posedness, followed by the existence and global stability of the endemic equilibrium. The disease‐free equilibrium and the basic reproduction number, , are computed in the absence of infective recruits, providing critical insights into disease dynamics. A sensitivity analysis is also conducted to assess the impact of parameter variations on the model outcomes. Using parameters estimated from World Organisation for Animal Health (WOAH) reports and numerical simulations (fourth‐order Runge–Kutta with a forward–backward sweep), we compute optimal control strategies and perform cost‐effectiveness analysis. Results show that the inflow of infectious animals through restocking can sustain transmission and weaken vaccination alone strategies, whereas combining biosecurity with vaccination and treatment achieves the largest reduction in infections per unit cost. These findings provide quantitative, policy‐relevant guidance for meeting national PPR eradication targets by prioritizing integrated control strategies over single‐intervention approaches.