Reticuloendotheliosis or Lymphoid Tumour Disease is a retrovirus infection that is common in chickens, turkeys, ducks, geese and quail with morbidity rates up to 25%. A gradual increase in mortality and reduced weight gain in broilers may be the first clinical signs of the disease. Clinical signs also include diarrhoea and leg weakness.
Transmission is lateral and possibly transovarian (from ovary to egg; type of vertical transmission), and the infection can be spread by mosquitoes or in contaminated Marek’s disease vaccines. There is an incubation period of 5-15 days.
Formal control programmes have not been documented as the condition is sporadic and relatively self-limiting. Avoidance of live vaccine contamination is the main control measure practised.