Molecular and Serological Detection of Newcastle Disease Virus in Native Chickens from Selected Live Bird Markets in Batangas, Philippines

At present, little information is known about the distribution of Newcastle disease virus(NDV) in live bird markets (LBMs) in the Philippines. Serological and molecular detection of NDVs in native chickens from different LBM in the Philippines were performed. Results showed that out of 49 sera tested, 48 (97.96%) were positive for NDV with hemagglutination-inhibition (HI) antibody titers ranging from 22 to 29 and geometric mean titer of 26.62.Except for respiratory signs, minor physical injuries and non-specific lesions, all native chickens did not show clinical signs of ND at the time of examination. Nested RT-PCR was performed on 76 oropharyngeal and cloacal swab samples and 49 pooled tissue samples. All results were negative for NDV. The unusually high HI antibody titers against NDV and the negative nested RT-PCR results may suggests that the examined birds may have been previously exposed to virulent NDVs but may have already recovered from clinical disease. Regular monitoring through disease surveillance and physical inspection of LBMs in the country should be regularly implemented to decrease the risk of transmitting NDV to the commercial poultry industry and prevent any future ND outbreak in the Philippines.