SEROPREVALENCE OF NEWCASTLE DISEASE IN DIFFERENT VACCINEAND PATHOLOGY OF CLINICALLY AFFECTED BIRDS
Abstract
Seroprevalence of Newcastle Disease (ND) in different vaccines in commercial layer chicken
was evaluated in different ages of grower and layer birds in different poultry farms of
Gazipur district. Seroprevalence was determined based on Hamagglutination Inhibition (HI)
test performed at Kazi farms poultry laboratory, Gazipur. Test report of six month
(January to June-2014) show that in grower birds (ages between 12-16weeks) prevalence of
ND was 12.5% and in layer (ages between 27-40 weeks) it was 26.6% and average
prevalence was 19.58%. For evaluation and comparison of ND commercial vaccine
effectiveness, about 10 farms (both grower and layer) were visited in Gazipur district. On
experimental “zero” day, randomly selected 10 birds in each farms were selected for HI test
and test results showed that, two grower farms (12 wks and 16 wks) and three layer farms
(27, 35 and 40 wks) were at low Antibody (Ab) titer level and it was geometric mean of log
(2
3.6 -3.9
) respectively. Then low Ab titre containing of these five farms
(randomly selected 10 birds in each farms) were vaccinated with three experimental vaccine
named Avinew
) and log (2
5.6 -5.8
(VG/GA Strain) and Newcastle disease vaccine (Mesogenic strain) on
grower birds and layer birds with Cevac New- L (Lasota strain) vaccine at experimental
“zero” day. After vaccination, blood serum were collected at 7
day of
following vaccination for HI test to determine Ab titre level of both experimental grower
and layer birds. Results showed the geometric mean of Ab titre level in case of grower birds
were log(2
th
and at 14
th
7.2 -7.6
day respectively and in case of layer birds it was
log (2
8.00 -8.1
and 2
th
) at 7
th
and 14
9.1- 9.2
) at 7th and 14th day respectively. Evaluation of vaccine efficacy on
age basis were determined by estimation of mean Ab titer level at experimental “zero” day of
vaccination and at 7
9.6 -10
and 2
day after vaccination. By statistical analysis, the mean titer
level of 7
th
th
and 14
th
th
and 14
days of following vaccination in both grower and layer groups were
highly significant (P<0.01) in comparison to the bird groups “Zero” day age groups.
Although birds were at different ages and farms were vaccinated by three different strains of
vaccines. At postmortem of clinically affected birds, subcutaneous edema in the neck,
petechial hemorrhages in proventriculus, congested and pneumonic lung, hemorrhagic liver
trachea and cecal tonsils were characteristic findings. Histopathologically, proventriculus
and trachea showed infiltration of inflammatory cells in the submucosa with mononuclear
cells and submucosal edema. Congestion in lungs, numerous inflammatory cells in cecum
and in liver hepatocellular necrosis infiltrated by mononuclear cells were found.