CLINICAL SIGNS AND TREATMENT

NDV- infected sick wild birds are predominantly found during late stages of disease. Information on initial signs is frequently lacking¹-⁹). However, occasionally wild birds with ND display lethargy, unilateral conjunctivitis and rhinitis, and birds succumb readily.

All virulent NDV strains cause systemic infections, which are expressed clinically in the following time sequence: severe lethargy, depression, anorexia, ruffled feathers, respiratory rales, cuffing, excretion of watery, greenish faeces and production of misshapen eggshells in laying females. As late sequelae, abnormal movements of the head and neck (torticollis), opisthotonus and unilateral lameness of wings and legs for prolonged times (all these signs persist for weeks to months). Feather tips of incoor­dinated wings display mechanical trauma. The duration of the disease may be as short as 2—3 days. Nervous signs may persist for many weeks to months in these cases; recovery is unlikely.

Mesogenic strains induce only minor respiratory signs. Lentogenic and avirulent-enteric strains are not associated with any clinical signs but seroconversion occurs.

There is no effective treatment of birds suffering from ND. Drugs such as amantadine or oseltamivir (Tamiflu) have no effect on penetration and uncoating of ND viruses.