Molecular Epidemiology of Newcastle Disease Virus in Backyard and Commercial Poultry in North Central Nigeria

This study investigates the molecular epidemiology of Newcastle disease virus strains circulating in backyard and commercial poultry populations in North Central Nigeria, characterising strain diversity, pathogenicity, and the epidemiological links between production systems. Newcastle disease is the most economically devastating avian disease in Nigeria, causing catastrophic losses particularly in village poultry that have limited vaccination coverage. Understanding viral strain diversity and transmission pathways between backyard and commercial systems is essential for designing effective vaccination and biosecurity strategies. This study collects 380 tissue and swab samples from clinically suspect and healthy birds in backyard, live bird markets, and commercial poultry operations across Niger, Kogi, and Kwara States. RT-PCR and full genome sequencing characterise viral strains. Phylogenetic analysis places strains within the global NDV classification. Fusion protein cleavage site analysis determines pathotype. Spatial analysis maps geographic distribution of strain types. Findings reveal that genotype VII virulent strains are the dominant circulating type, accounting for 74 percent of positive samples, and are genetically distinct from currently used vaccine strains, potentially contributing to vaccination failure. Identical strains are recovered from backyard and commercial birds in the same geographic areas, suggesting cross-system transmission through live bird markets. The study contributes original North Central Nigeria NDV molecular epidemiology data and recommends vaccination programme reform using contemporary genotype VII vaccines alongside live bird market biosecurity improvement.

Keywords: Newcastle disease virus, molecular epidemiology, North Central Nigeria, genotype VII, vaccination.