In Europe, some 70 confirmed HGA cases have been reported to date. However, seroepidemiological studies have revealed high (up to 21%) A. phagocytophilum antibody prevalences in some areas in Europe, suggesting that asymptomatic human infections might be common, A. phagocytophilum also has indirect implications for humans because it causes, for example, a tick-borne fever in livestock and febrile fevers in companion animals (cats and dogs) . Many wildlife mammalian species, such as rodents, shrews, and cervids, are naturally infected with A. phagocytophilum . Different genetic variants of A. phagocytophilum circulate in different tick and mammalian species, and these strains may differ in their pathogenicity to human. The distribution of A. phagocytophilum is worldwide .