Anaplasma phagocytophilum: An emerging but unrecognized tick-borne pathogen

Several vector-borne pathogens are considered to be emerging or re-emerging. Among these agents, Anaplasma phagocytophilum is a tick-borne rickettsiale bacterium of worldwide distribution. This bacterium is increasingly detected in several parts of the world in both ticks and hosts, including animals and humans. A. phagocytophilum is the causal agent of a zoonotic disease called ‘granulocytic anaplasmosis’ and described in several domestic animals and humans. Currently, human granulocytic anaplasmosis is considered to be the third most important vector-borne disease in both the USA and Europe and is also increasingly diagnosed in some Asian countries. However, in many parts of the world, this disease is unknown and no data are available on its epidemiology.

Key words: Anaplasma phagocytophilum, Granulocytic anaplasmosis, Epidemiology, Vector-borne disease, Zoonosis.