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The hematological lesions consequent upon velogenic Newcastle disease virus (NDV) infection were investigated in 6-week-old ducks and chickens. Following intramuscular inoculation, the results indicated significantly lower (p < 0.05) packed cell volume (PCV) in infected chickens (IC) on days 3 -9 post inoculation (PI) and in infected ducks (ID) on days 3 -15 PI. The hemoglobin concentrations were significantly lower (p < 0.05) in IC on days 3, 6 and 15 PI while in the ID, they were significantly lower (p < 0.05) on days 3, 9 and 15 PI. The total erythrocyte counts were significantly lower (p < 0.05) in IC on days 3, 9 and 15 PI and in ID, they were significantly lower (p < 0.05) on days 3 and 9 PI. The mean corpuscular values indicated macrocytic hypochromic anemia in IC and macrocytic normochromic anemia in ID. The leucogram showed leucopenia in IC and initial leucopenia followed by leucocytosis in ID. The hematological pictures of the velogenic NDV in this experiment indicate less susceptibility of ducks when compared with the chickens. The severity of this virus infection in chickens and the mild clinical signs and lesions presented by ducks showed that ducks are far less susceptible than chickens.

The effect of velogenic Newcastle disease virus (vNDV) on the immune responses and serum proteins was investigated in six-week-old ducks and chickens. Results showed that weight loss was markedly significant (p < 0.05) from days 3 -21 (PI) in chickens and mild (p < 0.05) on days 3 and 15 PI in ducks. The antibody response obtained showed significant (p < 0.05) increase in infected chickens (IC) than those of the infected ducks (ID). While the total serum protein and serum globulin increased significantly (p < 0.05) in IC on days 7 and 14 PI, they decreased significantly (p < 0.05) in ID only on day 21 PI. The immune responses and serum protein values in this experiment X-ray showed less susceptibility of ducks when compared with the chickens. This may be related to marked anorexia and severe dehydration observed in the latter consequent upon serum concentration. Ducks could be maintaining the endemicity of Newcastle disease (ND) as reservoir host.

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