Serological and molecular detection of Newcastle disease virus and identification of associated risk factors in chickens from Gondar City, Ethiopia

Abstract

Newcastle disease, caused specifically by virulent strains of Avian Paramyxovirus-1 (APMV-1), is a highly contagious viral disease of poultry that poses significant economic and food-security challenges in Ethiopia. Although the virus is widespread, information on the seroprevalence, molecular detection, and associated risk factors of Newcastle disease virus (NDV) in regions such as Gondar remains limited. Therefore, this study aimed to assess the serological and molecular detection of NDV and identify associated risk factors in chickens ( Gallus gallus domesticus ) in Gondar City, Ethiopia. A cross-sectional study was conducted from May to December 2024. A total of 384 serum samples were randomly collected from apparently healthy, non-vaccinated chickens and analyzed using a competitive enzyme-linked immunosorbent assay. In addition, nine pooled oropharyngeal swab samples were subjected to RNA extraction, followed by reverse-transcription polymerase chain reaction (RT-PCR) for molecular detection of NDV. The overall seroprevalence of NDV was 59.9%. Seropositivity was higher in exotic breeds (63.3%) than in local breeds (50.9%). Chickens managed under extensive systems showed greater seroprevalence (68.1%) compared with those under intensive (53.3%) or semi-intensive (54.5%) management. Flocks that introduced new chickens had significantly higher seroprevalence (67.7%) compared with flocks without new introductions (49%) (P < 0.05). Higher, though not statistically significant, seroprevalence was also observed in female chickens, adults, and layers. Molecular testing detected NDV in 27.8% of the pooled oropharyngeal swab samples. These findings highlight the widespread circulation of NDV in Gondar City and underscore the importance of routine vaccination, strengthened biosecurity practices, regulated poultry movement, and integrated surveillance to safeguard poultry health and productivity.