Authors: W S Ezema J O A Okoye J A Nwanta
Publish Date: 2008/07/24
Volume: 41, Issue: 4, Pages: 477-484
Abstract
Two groups of six weeks old cockerels comprising 40 immunized and 40 nonimmunized birds were inoculated intramuscularly with VGF1 which is a local Nigerian strain of velogenic Newcastle disease virus VNDV Immunized birds did not show any clinical signs except significant loss p 005 in body weight on days 5 and 20 post inoculation PI But the nonimmunized birds showed clinical signs of disease characterized by anorexia and drowsiness from day 2 PI These were followed on day 3 PI by depression diarrhoea opisthotonus weight loss p 005 and high mortalities 969 Both the immunized and nonimmunized groups showed severe atrophy of the bursa spleen and thymus Histopathological section of these lymphoid organs showed necrosis and depletion of lymphocytes Both the gross and microscopic lesions were more severe in the nonimmunized birds Marked ballooning degeneration was observed in the bursal follicles of the nonimmunized birds This lesion has not been described earlier for any other disease and could be diagnostic for VND Our results also showed that VND can cause marked atrophy of the lymphoid organs which may lead to immunosupression without the characteristic signs of Newcastle disease ND in vaccinated chickens This no doubt emphasizes the limitation of vaccination as a biosecurity measure in poultry industry
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