The Effect of Age on the Pathogenesis and Pathology of Newcastle Disease Virus Infection (NDV KUDU 113 Strain) in Chickens

Ezema, Sunday, Eze, Paul, Ezema, Nebechi and Ezema, Arinze

Objective: This study was designed to evaluate the effects of age on the pathogenesis and pathology of a local velogenic Newcastle disease virus (kudu 113 strain) infection in chickens. Methodology: Three hundred cockerels 3, 12 and 24 week of age were used in this study. Birds were divided into three batches. The first batch of birds (A) was raised to three weeks of age, the second batch (B) was raised to 12 weeks of age and the third batch (C) was raised to 24 weeks of age. Birds in each batch were further divided into challenged (n = 60) and unchallenged (n = 40) groups. Results: The Newcastle disease virus (NDV) infection showed highest morbidity rate was 100% by day 4 post inoculation (PI) in 3week old birds, 93.3% by day 5 PI in 12 week old birds and 25% by day 7 PI in 24 week old birds. Mortality rate of 100, 98 and 84% were observed in 3, 12 and 24 week old cockerels, respectively. The highest percentage of live body weight loss of 46.0, 44.0 and 27.8% were observed in 3, 12 and 24 week old cockerels, respectively. Gross lesions of NDV infection such as atrophy, of the Bursa of Fabricius, proventricular hemorrhages, hemorrhagic swollen cecal tonsil and sharply demarcated intestinal ulcers were observed in the three different age groups in various days PI but the severity of lesions and distribution varied. The mean lesion scores were 30.2, 49.0 and 19.0 in 3, 12 and 24 week old cockerels, respectively. The geometrical mean titer (GMT) of NDV antibody of 3 week of cockerels significantly (p<0.5) decreased from 21.1-3.5 by day 3 PI, which later increased significantly (p<0.05) to 42.2 and 512 on days 6 and 9 PI, respectively. But the GMT of twelve week old birds significantly (p<0.05) increased from 2.0-19.7, 78 and 2048 on days 6, 9 and 21 PI, respectively. While the GMT of twenty four week old birds significantly (p<0.05) increased from 0-78.8, 477.7 and 2531.4 on days 6, 9 and 21 PI, respectively. Conclusion: The result of this study has shown that age influences the pathology and pathogenesis of NDV infection in birds.

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