History and clinical findings: A 49-year-old travel guide fell ill during his return from a 6-week-stay in Vietnam, Myanmar and Thailand. He developed high fever and severe headache. On admission, the body temperature was at 39.5 degrees C with relative bradycardia. A black, crusted skin lesion of approximately 5 mm diameter was noted on the chest wall and was interpreted as an insect bite.
Investigations: CRP and liver enzymes were elevated. Total leucocyte count was normal but the differential count showed a left shift and aneosinophilia. Imaging procedures revealed splenomegaly and small pleural effusions on both sides.
Treatment and course: The patient was treated with a parenteral quinolone based on the initial suspicion of typhoid fever. Failure of this treatment and negative blood cultures raised concerns about the possibility of Tsutsugamushi fever, based on travel history and a re-evaluation of the skin lesion as an eschar. Tsutsugamushi fever was suspected on epidemiological and clinical grounds and was confirmed by the detection of specific IgM to Orienta tsutsugamushi and by seroconversion of IgG antibodies during follow-up. Even before immunodiagnostic confirmation was available, a course of doxycycline was started. This led to rapid improvement of the patient's condition.
Conclusion: In febrile travellers returning from Southeast Asia, Tsutsugamushi fever has to be considered in the differential diagnosis. The causative agent, Orienta tsutsugamushi is transmitted by larvae of trombiculid mites (chiggers). Leading symptoms are fever continua, cephalgia, and a primary lesion (eschar) at the site of cutaneous inoculation. The Eschar is easily overlooked and has to be searched carefully. Diagnosis is confirmed by the detection of specific antibodies. However, serology may be negative in the beginning. Therefore, treatment with doxycycline should be initiated on clinical grounds.