Background: Ticks and tick-borne infections will most probably increase in Norway due to global warming, regrowth of pastures and an increasing number of cervids. A. phagocytophilum is already a common infection among domestic ruminants and cervids in tick (Ixodes ricinus) infested areas in Norway.
Material and methods: The article provides a review of A. phagocytophilum infection in mammals, with a special focus on human anaplasmosis. It is based on relevant literature and the author's extensive research on this bacterium.
Results and interpretation: A. phagocytophilum infection may cause a tick-borne disease. Although the infection is widespread in animals along the coast of southern Norway, only few human cases have been reported so far. This discordance may indicate that physicians are not adequately aware of the disease's existence and that few clinical laboratories offer diagnostic testing of human anaplasmosis and/or infection of humans with low virulent variants of A. phagocytophilum. Even though infection with A. phagocytophilum mainly presents as a influenzae-like disease it may have a fatal outcome. Human anaplasmosis should be considered as a differential diagnosis when faced with a patient with influenzae-like symptoms 1-3 weeks after a tick bite.