Ds. Christopher et al., INFECTIOUS BURSAL DISEASE - INFLUENCE OF VVIBDV ON IMMUNITY TO RANIKHET-DISEASE AT THE FIELD LEVEL, Indian Journal of Animal Sciences, 67(10), 1997, pp. 833-835
The seroepidemiological data of Ranikhet disease (RD) and infectious b
ursal disease (IBD), before (during 1991-92) and after (during 1993-94
) the outbreak of very virulent form of IBD (vvIBD) in Tamil Nadu, wer
e statistically analysed. During 1993-94 the half-life (t(1/2)) of RD-
maternally derived antibodies (RD-MDA) was 3.2 days and the IBD-MDA wa
s 4.11 days in clean premises. In the infected premises t(1/2) of the
RD-MDA was 2.69 days and the t(1/2) of RD-vaccinal antibodies was 1.85
days. The observed RD vaccinal titres of samples collected during 199
3-94 are significantly lower than the statistically predicted HI-titre
s (using 1991-92 titres as the base), for that age. Mathematical concl
usions indicate that vvIBDV could be the cause of this perceived diffe
rence in the RD-HI titre values.