Abstract
Field survey of broiler poultry farms suspected to be infected with Newcastle disease (ND) was carried out during an
outbreak in district Faisalabad, Punjab in 2012. The validity of different diagnostic methods; like virus isolation,
identification and two-step Reverse Transcriptase Polymerase Chain Reaction (RT-PCR), was assessed and compared for the
effective and rapid diagnosis of ND virus (NDV). Moreover, suitability of different postmortem samples (pooled tissues) and
clinical samples (tracheal swabs) was also evaluated for efficient diagnosis. A higher rate of NDV detection was found with
pooled tissue samples than tracheal swabs with virus isolation, identification and RT-PCR tests. Coefficient of agreement (K
value) was calculated and a perfect and substantial agreement was found between both antigen-detection assays with K value
of 0.82 and 0.72 when applied on pooled tissues samples and tracheal swabs, respectively. After molecular detection of
NDV, a significant relationship was observed between nervous signs and RT-PCR (P<1.00), while a non significant
relationship of RT-PCR results was recorded with enteric and respiratory signs (P<0.08- 0.48). Data obtained from the field
study suggests that pooled tissue samples are more suitable for the detection of NDV than tracheal swabs with both of the
diagnostic techniques. Moreover, NDV detection rate was higher with RT-PCR than the conventional virus isolation and
identification method along with an additional advantage of being quick to perform which is a basic necessity in case of ND
outbreaks
