A leukosis in turkeys associated with infection with reticuloendotheliosis virus

The clinical features and lesions are described for an outbreak of a leukosis in an integrated turkey breeding organisation. Turkeys had diarrhoea between 8 and 12 weeks of age and from 15 weeks onwards leukosis lesions appeared. A greater than 20% mortality occurred in most affected flocks. The disease was characterised clinically by enlargement of the liver and to a lesser degree other organs. Microscopically the lesions consisted of proliferations of lymphoblastoid cells. Reticuloendotheliosis virus (REV) was isolated from ailing culled turkeys and from cell cultures prepared from embryonated eggs produced by a flock with this disease. In affected flocks a REV was also isolated from turkeys 8 to 12 weeks of age in which enteritis was the main clinical feature. Inoculation of 1-day-old turkeys with this isolate of REV produced a syndrome of enteritis followed by leukosis. Antibody to REV was detected in turkeys surviving experimental inoculation and in the two flocks of turkeys examined, one of which had experienced considerable leukosis mortality.