Haemobartonellosis (Eperythrozoonosis)
Johanna L. Watson • Gary P. Carlson
Haemobartonella bovis is an epicellular organism closely associated with the surface of erythrocytes. It may appear as a rod shape, an ovoid, or in chains with conventional stains.
Haemobartonella, or hemotropic mycoplasma, infection is primarily of academic interest in North America; it is rarely a cause of anemia. The organism has been found in association with other rickettsial diseases and has been experimentally transmitted in splenec- tomized calves. The agent may be visualized as delicate ovoid, rod, or dumbbell forms arranged in chains or tight groups or randomly distributed epicellularly throughout appropriately stained blood smears.Eperythrozoonosis in Cattle
The causal agent is Eperythrozoon wenyonii (Mycoplasma wenyonii). Infection is usually latent, producing no clinical signs in normal cattle, but it may become apparent in animals that have been severely stressed by some other systemic disease. The disease can be produced experimentally if infected blood is administered to splenectomized calves. Even under experimental circumstances, clinical signs consist of mild depression, fever, and modest anemia. The disease in cattle is of little clinical consequence except for the potential for confusion should the organism be seen on stained blood films. Occasionally cattle may have swollen and tender teats and legs.1
Eperythrozoonosis in Sheep and Goats
The causal organism in sheep and goats is Mycoplasma ovis (Eperythrozoon ovis), which appears to be similar morphologically and serologically to that found in cattle. The disease can produce more prominent clinical signs in sheep, with profound depression, anemia, and significant death losses in young lambs.2 Red cell destruction is thought to be caused by intravascular hemolysis and erythrophagocytosis.