No abstract

A disease associated with central nervous system signs was observed in two duck flocks, each consisting of 6000 three-week-old ducklings, a week after their arrival at the receiving farms.The clinical signs included leg weakness, dyspnoea, diarrhoea, and in many cases disturbance of equilibrium, retrograde movemenr; torticollis and twisting of the neck. Pathological and histopathological examinations revealed lympho-histiocytic meningitis and cerebroventriculitis, airsacculitis with moderate amounts of fibrinous exudate, bronchitis associated with formation of lymphoid follicles, focal or interstitial pneumonia, in some cases with fibrinous serositis, interstitial catarrh and splenomegaly. Large numbers of mycoplasmas were seen by electron microscopy and were isolated from the affected meninges and pericardium.Other diseases were excluded by laboratory examinations. The isolates were identified as Mycoplasma anatis. The pathogenicity and immunogenicity of the strain were investigated in an infection experiment in ducks. Although during this experiment no disease associated with clinical signs or deaths occurred, birds infected into the airsacs or intracranially exhibited pathological lesions similar to, but milder than, those seen in the field outbreak. No immune response was detectable by the serological and cellular tests applied. The pathological significance of M . anatis infection in ducks merits further study.