VOLUME 19 NUMBER 2 (July to December 2026)

Seroprevalence and risk factors of Newcastle disease virus in unvaccinated backyard chickens in Bukidnon, Philippines

Newcastle disease (ND) remains a significant threat to poultry production in the Philippines, particularly within smallholder backyard systems. This cross-sectional serological survey evaluated the seroprevalence of ND antibodies and assessed associated risk factors among unvaccinated backyard chickens in selected areas of Bukidnon. A total of 288 blood samples were collected from chickens in four study areas in Bukidnon: two municipalities (Manolo Fortich and Quezon) and two cities (Malaybalay City and Valencia City). An indirect enzyme-linked immunosorbent assay (ELISA) was employed to detect ND antibodies, and associations between seropositivity and potential risk factors were analyzed using chi-square tests and odds ratio estimates. The observed and true prevalence of ND antibodies were 12.50% (95% CI: 8.68–16.32%) and 12.71% (95% CI: 8.86–16.56%), respectively. However, no statistically significant differences in ND seroprevalence were found among the study areas (p > 0.05). Confined housing posed the greatest threat (OR = 10.23), followed by feeding through/bowl (OR = 3.22), and age segregation (OR = 2.63). The detection of ND antibodies in unvaccinated backyard chickens indicates natural exposure to ND virus within the surveyed areas. These findings are important in biosecurity, vaccination strategies, and enhanced ND surveillance in smallholder poultry systems to inform evidence-based husbandry and management practices, thereby mitigating viral transmission and preventing disease outbreaks.