Lymphoproliferative disease of turkeys 1. Clinical aspects.

Several outbreaks of a lymphoproliferative disease of turkeys were investigated. The disease affected birds from 10 weeks of age onwards and resulted in mortality figures often in excess of 20%. The disease was characterised clinically by gross splenomegaly with focal lesions in most organs, and infiltration of the peripheral nerves. Microscopically lesions consisted of focal proliferations of lymphoid cells and plasma cells. Ultrastructural studies confirmed the pleomorphism of the proliferating cells and virus particles were demonstrated in spleen, liver and thymus.