A genus of organisms in the family Anaplasmataceae, order Rickettsiales. Members parasitize erythrocytes, thrombocytes and leukocytes and are transmitted by ticks.
- A. bovis — causes benign bovine rickettsiosis in Asia and Africa. Previously Ehrlichia bovis.
- A. caudatum — often found in mixed infections with A. marginale in cattle.
- A. centrale — causes a mild form of anaplasmosis in cattle and has been used as a vaccine against A. marginale.
- A. marginale — a significant pathogen, the cause of anaplasmosis in ruminants. The infection is transmitted mechanically by many biting insects. Ticks, including Boophilus spp. and Dermacentor spp., are biological vectors.
- A. ovis — the cause of anaplasmosis of sheep.
- A. phagocytophilum — causes tickborne fever or ‘pasture disease’ in cattle, goats, sheep and wild ruminants; granulocytic ehrlichiosis in cattle, cats and llamas, both of which are characterized by leukopenia and thrombocytopenia, equine ehrlichiosis, and human granulocytic ehrlichiosis. Transmitted by Ixodes ticks. Previously Ehrlichia equi (Rickettsia phagocytophila and Rickettsia equi), E. phagocytophila and the human granulocytic ehrlichiosis (HGE) agent.
- A. platys — the cause of canine infectious cyclic thrombocytopenia. The only rickettsia known to infect platelets. Thought to be transmitted by Rhipicephalus sanguineus. Previously called Ehrlichia platys.
