[Human granulocytic ehrlichiosis in Norway].
BACKGROUND: The bacterium that causes human granulocytic ehrlichiosis may be transmitted by ticks. MATERIAL AND METHODS: We describe two patients with human granulocytic ehrlichiosis. During the summer of 1998, both patients were bitten by ticks. Four to 7 days later they developed influenza-like symptoms with fever, headache and myalgia. After 4 and 21 days, respectively, both patients were given doxycycline for suspected bacterial respiratory diseases, and recovered. RESULTS: Blood samples for human granulocytic ehrlichiosis antibodies showed a fourfold increase in titer in one patient and a remaining high titer in the other. Both patients had a positive polymerase chain reaction with primers specific for the Ehrlichia phagocytophilae genogroup. INTERPRETATION: The two patients fulfill the human granulocytic ehrlichiosis diagnostic criteria set by Centers for Disease Controls and Prevention, and are the first two human granulocytic ehrlichiosis cases described in Norway.