The onset tends to be gradual, with prodromal symptoms of headache, malaise, backache, and chills. These symptoms are followed by a shaking chill, fever, and more severe headache accompanied by nausea and vomiting. A remittent pattern of fever accompanied by tachycardia continues for 10 to 12 days in the untreated patient and then subsides. The rash typically appears around the fifth day of fever. Discrete, irregular pink macules first appear in the axillae and on the inner surface of the upper arms, and then other lesions quickly develop on the trunk, the thighs, and the upper arms.
Lesions are sparse on the face, the palms, and the soles.
In mild cases, it may be very transient. Rash is not seen in 20 to 46 percent of cases. Pulmonary manifestations, which are caused by rickettsial involvement rather than bacterial superinfection, are common. A nonproductive cough develops, and in the second week of illness, patchy pulmonary infiltrates may be seen on x-ray, often in the absence of any physical findings. As in RMSF and epidemic typhus, headache is a prominent symptom and continues well into the second week of untreated illness.