Peste Des Petits Ruminants: From Virus–Host Interactions to Risk-Based Global Eradication

Peste des petits ruminants (PPR) is a major transboundary disease of small ruminants, and the FAO–WOAH strategy sets 2030 as the target for its global eradication. Despite advances in virology, diagnostics and vaccination, eradication remains challenging because of spatial variation in transmission risk, uneven population immunity, surveillance gaps, cold-chain constraints and animal movements. This review links virus–host interactions to pathogenesis, clinical presentation, diagnostic selection and vaccination practice, while distinguishing experimentally supported mechanisms from questions that remain unresolved in naturally infected populations. We also propose four Operational Risk States as a subnational decision-support overlay to the official eradication programme. The overlay integrates evidence on virus circulation, outbreak history, population immunity, surveillance adequacy, reintroduction risk and intervention feasibility to guide the intensity of vaccination, active surveillance, scenario-specific diagnosis, movement management and genomic investigation. It adds explicit assignment criteria and review triggers but does not replace FAO–WOAH programme stages or WOAH requirements for official freedom. The review further clarifies that seroprevalence is not equivalent to protection, emerging diagnostic platforms require scenario-specific validation, differentiating infected from vaccinated animals (DIVA) is a vaccine–diagnostic strategy rather than a platform, and vector immunity and cold-chain limitations require product-specific evaluation. Sustainable eradication will depend on integrated decision-making of which the effectiveness is evaluated prospectively under field conditions.