Avian Metapneumovirus Subtype B at the Wildlife–Poultry Interface in Egypt: Molecular and Serological Insights into Cross-Ecological Transmission

Abstract

Avian metapneumovirus (aMPV) is a major respiratory pathogen of poultry with a significant economic impact; however, its epidemiology at the wildlife–poultry interface remains poorly understood, particularly within Afro–Eurasian migratory systems. This cross-sectional study (December 2024–April 2026) investigated aMPV occurrence in wild birds across eleven Egyptian governorates representing key ecological zones along major migratory flyways. A total of 1280 samples were collected from 800 wild birds representing migratory waterfowl and synanthropic species, including 800 oropharyngeal swabs tested by real-time RT-qPCR for aMPV subtypes A and B and 480 serum samples analyzed using indirect ELISA. aMPV RNA was detected in 28/800 samples (3.5%), with all positives identified as subtype B and confined to the Nile Delta, Middle Egypt, and Canal Region. In contrast, serological analysis revealed a high seroprevalence of 58.3% (280/480), indicating widespread prior exposure with significant spatial and species-level variation (p < 0.05). The marked disparity between low molecular detection and high seroprevalence supports transient infection with cumulative exposure. The exclusive detection of subtype B may reflect epidemiological connectivity between poultry and wild bird populations within shared ecological interfaces; however, the directionality of transmission and the possibility of independent wildlife maintenance could not be determined within the scope of the present cross-sectional study. Future studies incorporating whole-genome sequencing, longitudinal surveillance, and broader flyway-scale sampling are needed to resolve transmission pathways and distinguish field strains from potential vaccine-derived viruses within wildlife–poultry interfaces.