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Swedish University of Agricultural Sciences

Veterinary bacteriology: information about important bacteria
Veterinary bacteriology


Species/Subspecies: Anaplasma phagocytophilum
Category: Zoonotic
Etymology: Genus name: a thing without shape.
Species epithet: is attracted by phagocytes.
Significance:Most common during late spring, summer and autumn in Sweden.
  [Very important]   
Old Species Name(s):Ehrlichia equi, Ehrlichia phagocytophila and the HGE-agent have been transferred to one species, Anaplasma phagocytophilum.
Taxonomy:
Phylum
Proteobacteria
Class
Alphaproteobacteria
Order
Rickettsiales
Family
Anaplasmataceae 
Genus
Anaplasma
Type Strain: Webster
Macromorphology (smell): Cannot be cultured in cell-free media (for instance agar plates).
Micromorphology:
   
Small pleomorphic and non-motile cocci (0.3-0.4 µm in diameter). Blood smears ("buffy coat smears") are stained by Giemsa or acridine orange staining. The bacteria can then be seen in the granulocytes as small bluish-lilac or orange red, respectively, coccoid rods inside inclusions (so-called morulae). A morula (see below) can be up to 6 µm in diameter.
Gram +/Gram -:G-. Is, however, normally not gram stained.
Metabolism: Aerobic
Catalase/Oxidase:
Fermentation of carbohydrates: Is not used for identification of Anaplasma spp. because it may be difficult to differentiate the metabolism between the bacterium and the host cell. Furthermore, many intracellular bacteria lack enzymes for carbohydrate metabolism because of evolutionary gene reduction.
Spec. Char.:
Vector:
Anaplasma phagocytophilum  
The bacteria are transmitted by ticks (primarely Ixodes ricinus in Sweden) and are not contagious between individuals.
Reservoir: Small rodents and wild ruminants etc.
Disease:
HostsDiseaseClinical picture
HorseAnaplasmosisHigh fever, inappetence, limb oedema, ataxi, icterus and petchial haemorrhages on mucous membranes
RuminantsAnaplasmosis, Tick-borne fever, pasture feverHigh fever, drop in milk production, inappetence, abortion, leukopenia, ataxia
HumansAnaplasmosisFever, headache, myalgia (pain in muscles), nausea, abdominal pain, diarrhea, neurological symptoms, redness of the skin may occur.
Genome Sequence:
Acc-noStrainSize (bp)Genome
NC_007797 HZ 1 471 282 1c + 0 

16S rRNA Seq.:
Acc-noStrainNumber of NTOperon
AF172164 CASOLJ 1 395 

Taxonomy/phylogeny:
 
Seven species have been described within the genus Anaplasma, which is most closely related to the genus Ehrlichia.
Comment:Intracellular, inclusions (morulae) in eosinofilic and neutrofilic granulocytes. Morula refers to the structure, which resembles mulberrys (Latin Morus, mulberry). Tetracyclines are used for treatment but the disease can heal without treatment.
Reference(s): No. 5, 66, 80
Updated:2021-08-07

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