Reticuloendotheliosis can occur in birds (i.e. avian reticuloendotheliosis), which is caused by a reticuloendotheliosis virus (from a group of retrovirus). Reticuloendotheliosis in humans, e.g. leukemic reticuloendotheliosis, is a hereditary disorder of the reticuloendothelial system characterized by enlarged spleen (splenomegaly) and abnormally high number of hairy mononuclear cells in bone marrow, spleen, liver and peripheral blood.
See also: reticuloendothelial system