Incidence of human granulocytic anaplasmosis is rising in Maine, USA. This increase may be explained in part by adoption of tick panels as a frequent diagnostic test in persons with febrile illness and in part by range expansion of Ixodes scapularis ticks and zoonotic amplification of Anaplasma phagocytophilum.
Keywords: Anaplasma phagocytophilum; Ixodes scapularis; Maine; anaplasmosis; bacteria; deer tick; tickborne disease testing; vector-borne infections; zoonoses.