Meningeal signs and CSF pleocytosis are common during the second phase. The incubation period usually lasts 7 to 12 days, with a range of 2 to 20 days. Most patients have an anicteric, self-limited illness clinically indistinguishable from viral or bacterial infections. Fever may be the only manifestation. The onset of acute disease is abrupt and is typically manifested by high fever, chills, headache, and prostration.
Myalgias are prominent.
Maculopapular, petechial, or purpuric rashes may appear, usually on the trunk. Splenomegaly, hepatomegaly, and lymphadenopathy are uncommon. Coincident with the disappearance of leptospires from the circulation and CSF is an afebrile, almost symptom-free period, usually lasting from 1 to 3 days. Then a second phase is heralded by the return of fever and other earlier symptoms. Meningismus, photophobia, uveitis, and CSF pleocytosis are common.