In recent years, the incidence of tick-borne diseases has been steadily increasing. Anaplasma phagocytophilum is a Gram-negative obligate intracellular bacterium transmitted by ticks of the Ixodes genus. Human granulocytic anaplasmosis typically presents with fever, headache, chills, malaise, and myalgia, while rash and gastrointestinal or respiratory symptoms occur less frequently. We report the case of a 47-year-old woman with no significant past medical history who was admitted to the infectious diseases department with suspected central nervous system infection. Symptoms began suddenly three days before admission and included high fever up to 41°C and severe paroxysmal headaches accompanied by nausea and unresponsive to analgesic therapy. The patient reported removal of a tick approximately two weeks prior to symptom onset. Due to markedly elevated D-dimer levels (26,430 ng/ml), urgent contrast-enhanced computed tomography with venography was performed, which excluded cerebral venous sinus thrombosis. Cerebrospinal fluid analysis was normal. Serological tests for Lyme borreliosis and tick-borne encephalitis were negative. Because of suspected anaplasmosis, PCR testing for Anaplasma phagocytophilum was performed and returned positive. Treatment with doxycycline led to complete resolution of symptoms within eight days of hospitalization.