Taxonomy

• Order: Rickettsiales.
• Family: Anaplasmataceae (formerly Rickettsiaceae).
• Genus:
  • Anaplasma.
  • Ehrlichia.
  • Neorickettsia.
  • Wolbachia.
• The Family Anaplasmataceae now contains four genera.
• Ehrlichiae were initially grouped according to type of blood cell most commonly infected (granulocyte, lymphocyte, monocyte, platelet), and disease classes have been termed “granulocytic (or granulocytotropic) ehrlichiosis” or “monocytic (or monocytotropic) ehrlichiosis”. However, this type of classification may be misleading because some of the Ehrlichia species have been found in cells other than their chief target cell type. In addition, more than one species may be responsible for the broad category of “monocytic” or “granulocytic” ehrlichiosis.

Classification and Nomenclature changes for Ehrlichia and related species

• • The tribe Ehrlichieae and the genus Wolbachia are in the Family Anaplasmataceae.
  • Ehrlichia equi and E. phagocytophila become Anaplasma phagocytophilum (Ehrlichia equi).
  • Ehrlichia platys becomes Anaplasma platys.
  • Ehrlichia senetsu and E. risticii become Neorickettsia sennetsu and N. risticii respectively.
  • Cowdria ruminantium becomes Ehrlichia ruminantium.
  • Haemobartonella spp and Eperythrozoon spp become Mycoplasma spp.

Etymology

• Anaplasma: Gk. an-, without; plasma-, anything formed or molded.

• A. phagocytophilum Anaplasma phagocytophilum (the organism) and A. platys have a worldwide distribution.
• N. helminthoeca Neorickettsia helminthoeca is distributed along the western coast of North America from California to Vancouver.
• E. canis Ehrlichia canis, E. ewingii, and E. chaffeensis have a worldwide distribution, although are most commonly found in the Asia-Pacific region.

• Canine granulocytic ehrlichiosis Ehrlichiosis is caused by three Anaplasmataceae species:
  • E. canis Ehrlichia canis.
  • E. ewingii.
  • E. chaffeensis. Potentially zoonotic.
• Canine cyclic thrombocytopenia Thrombocytotropic anaplasmosis is caused by A. platys. Potentially zoonotic.
• Canine granulocytic anaplasmosis Anaplasmosis: Anaplasma phagocytophilum is casued by A. phagocytophilum Anaplasma phagocytophilum ( the organism). Potentially zoonotic
• Salmon poisoning disease Salmon poisoning disease is caused by N. helminthoeca Neorickettsia helminthoeca.

Refereed papers

• Recent references from PubMed and VetMedResource.
• Aziz M U, Hussain S, Song B et al (2023) Ehrlichiosis in Dogs: A Comprehensive Review about the Pathogen and Its Vectors with Emphasis on South and East Asian Countries. Vet Sci 10 (1), 21 PubMed.
• Atif F A,  Mehnaz S, Qamar M F et al (2021) Epidemiology, Diagnosis, and Control of Canine Infectious Cyclic Thrombocytopenia and Granulocytic Anaplasmosis: Emerging Diseases of Veterinary and Public Health Significance. Vet Sci 8 (12), 312 PubMed.
• El Hamiani Khatat S, Daminet S, Duchateau L, et al (2021) Epidemiological and Clinicopathological Features of Anaplasma phagocytophilum Infection in Dogs: A Systematic Review. Front Vet Sci PubMed.
• Keyte S, Abdullah S, James K et al (2021) Prevalence and distribution of Anaplasma phagocytophilum in ticks collected from dogs in the United Kingdom. Vet Rec 188 (8) PubMed.
• Smith F D & Wall L E (2013) Prevalence of Babesia and Anaplasma in ticks infesting dogs in Great Britain. Vet Parasitol 198 (1-2), 18 – 23 PubMed.
• Dumler J S, Barbet A F, Bekker C P et al (2001) Reorganization of Genera in the Families Rickettsiaceae and Anaplasmataceae in the order Rickettsiales; Unification of some species of Ehrlichia with Anaplasma, Cowdria with Ehrlichia, and Ehrlichia with Neorickettsia; Description of six new species combinations; and designation of Ehrlichia equi and “HGE agent” as subjective synonyms of Ehrlichia phagocytophilum. Int J Syst Evol Micorbiol 51 (6), 2145-2165 PubMed.