Background: In April 2004, the Norwegian Institute of Public Health was notified about an outbreak of a respiratory illness among participants on a cultural-historical theme tour to Central America. One patient was examined in a Swedish hospital where the clinician suspected histoplasmosis, which later was verified by serology and by culture of Histoplasma capsulatum. In order to describe the outbreak and identify the possible source of infection, a clinical and epidemiological study was conducted.
Material and methods: A questionnaire on symptoms, treatment and participation in various activities was sent to all the tour participants. Reminders were sent by e-mail. In addition, some participants underwent a more detailed clinical examination.
Results: 19 of the 21 travellers completed the questionnaire. All travellers had visited several caves inhabited by bats in El Salvador and Guatemala. During the last 10 days of the journey, 16 of the respondents (84%) acquired a respiratory illness that lasted for more than 3 weeks. The diagnosis was confirmed by serology in 8 of the 14 tested cases. Antibacterial therapy was given to 11 patients and antifungal therapy to 3 patients. Only one patient was hospitalised.
Interpretation: The described outbreak of histoplasmosis was probably caused by exposure to Histoplasma capsulatum during a visit in bat-infested caves. Due to the increasing popularity of adventure and theme travels, this disease may become more frequent in our population. The condition should be considered in travellers with prolonged respiratory illness after visits to caves or other closed environments with little circulation of air that are potentially contaminated with bat or bird droppings. Persons with immunosuppression may develop severe illness, and should consider avoiding places with increased risk.