SIGNIFICANCE AND IMPLICATIONS FOR ANIMAL HEALTH
Several Rickettsia and Anaplasma species, as well as E. canii, have veterinary significance, being associated with infections in livestock and/or companion animals. Rickettsia conorii infections have been occasionally reported in dogs, and evidence that such infections may be more common than currently recognized.
The seroprevalence of antiRickettsia antibodies in southern European dogs is remarkably high. Anaplasma phagocytophilum is a significant pathogen of sheep and cattle in I. ricinus-infested upland regions of North-western Europe. It is associated with tick- borne fever and tick pyaemia, perhaps affecting 1% of the national flock. A. phagocytophilum-induced disease, akin to that described for humans, has also been reported in other livestock and companion animals, demonstrating the ‘generalist’ character of the species. Other Anaplasma species are far more host-specific: A. marginale causes bovine anaplasmosis, which is encountered in tropical and subtropical areas throughout the world and is a major constraint to cattle production in many countries; A. ovis provokes a similar disease, but in sheep and goats rather than cattle; A. centrale is also a pathogen of cattle, but provokes only mild disease; A. platys is responsible for infectious cyclic thrombocytopenia in dogs, which has been described throughout the world. Ehrlichia canis is the agent of canine monocytic ehrlichiosis, a potentially lifethreatening infection.References for further reading are shown below(1-7).
REFERENCES
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The natural history of Anaplasma marginale. Veterinary Parasitology. 2010;167:95-107.
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Little, S.E. The increasing recognition of rickettsial pathogens in dogs and people. Trends in Parasitology. 2010;26:205-12.
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7. Walker, D.H. & Ismail, N. Emerging and re-emerging rickettsioses:
endothelial cell infection and early disease events. Nature Reviews Microbiology. 2008;6:375-86.