Molecular Detection Of Newcastle Disease Virus In Clinically Suspected Broiler Chickens From Kirkuk Province, Iraq: Paired Comparison Of Tracheal Swabs And Blood Samples

Abstract

NDV is still considered a major limiting factor on poultry farming in endemic areas. In this field study, we report the presence of NDV RNA in clinically affected broilers in Kirkuk Province, Iraq, comparing paired tracheal swabs and blood samples for conventional RT-PCR detection. A total of 96 broiler chickens with clinical symptoms of NDV infection at the age of 3-6 weeks old from four commercial farms in Kirkuk were selected. One tracheal swab and one blood sample were collected from each chicken and subjected to conventional RT-PCR using specific primers for NDV, which targets the F gene with expected amplification of 387 bp. NDV RNA was detected in 19 out of 96 (19.8%; 95% confidence interval [CI]: 13.1-28.9%). NDV RNA was found in 18 chickens in tracheal swabs (18.8%), while six were positive in blood samples (6.3%). Five chickens were positive in both sample types, thirteen in tracheal swabs, and one in blood. The detection rate in tracheal swabs was significantly higher than that in blood samples (McNemar's exact test, P=0.0018). While the clinical and post-mortem lesions were consistent with NDV infection, it was not enough to classify the virus genotype, pathotype, or virulence.