Clinico-pathological and Immunohistochemistry of Newcastle Disease in Indigenous Chickens and Some Wild Birds in Plateau State, Nigeria

Aim: Newcastle disease (ND) is one of the most important avian diseases. Virulent strains of Newcastle disease virus (NDV) have the potential of rapid spread, and may cause serious economic impact and international trade restrictions for the poultry industry. The objective was to study the clinical, gross and histo-pathological and immunohistopathological changes of Newcastle disease infection in apparently healthy and sick indigenous chickens, ducks, pigeons and some wild birds in Plateau State.

Methodology: The indigenous chickens used in this study were randomly selected from apparently healthy and from those with suggestive clinical signs of ND. A total of 638 birds were used for the study. Out of the total number of birds sampled, 349 were indigenous chickens, 98 pigeons, 96 ducks and 95 from different species of wild birds. Out of the number sampled from indigenous chickens, 169 (44.01%) were live birds, while 180 (46.90%) were carcasses. Tissues were collected from indigenous chickens, pigeons, ducks and some wild birds from both sick, and apparently healthy unvaccinated flocks to screen for the presence of NDV by immunohistochemical (IHC) techniques. The histopathology and immunohistochemistry were done using standard laboratory procedures.

Results: Clinical signs observed in live birds generally varied from weakness, greenish watery diarrhoea, respiratory difficulty, anorexia and coughing, torticollis, droopy wings, paralysis, partial leg paralysis, and opisthotonos. Generally, the gross lesions in euthanized and dead birds were mostly hyperaemia, hepatomegaly, splenomegaly, moderate enlargement of the heart, petechial haemorrhages on the mucosa surface of the proventriculus and haemorrhagic tracheitis, congestion and moderate enlargement of the pancreas, pulmonary congestion and congested kidneys. Histopathological changes include lymphoid depletion and connective tissue proliferation, enteritis, pulmonary congestion and splenitis. A total of six samples (1.56%) out of 349 from indigenous chickens had positive staining for NDV antigen using IHC technique. While there were only two samples out of the 95 wild birds samples positive by IHC, both of the positive samples were from Red-eyed Dove (Streptopelia semitorquata), resulting in a 25% (2/8) positive rate from this species; had positive staining for NDV by immunohistochemistry. All IHC positive cases in this study, in both wild birds and indigenous chickens shared similar staining patterns.

Conclusion: The study also shows that NDV antigens in wild birds and indigenous chickens concentrate more in the spleen, pancreas, trachea and proventriculus. This study, presents for the first time to the best of our knowledge that viral antigens (NDV) in wild birds and indigenous chickens were demonstrated by immunohistochemical technique in Plateau State, Nigeria.