An outbreak of acute pulmonary histoplasmosis among travelers to a bat-inhabited cave in Brazil

Abstract

Histoplasmosis is known to be endemic in various parts of the world, especially in North and Latin America. In Japan, Histoplasma capsulatum has rarely been isolated from the natural environment. To date, only seven cases of histoplasmosis have been reported in Japan including some that were contracted in foreign countries. Herein, we report the occurrence of acute histoplasmosis among Japanese travelers who were exposed to bat guano in a cave near Manaus, Brazil. A group of 8 Japanese travelers entered a cave for a total of 2 hours in March, 1993. All the visitors had been healthy and had no history of abnormal chest roentgenograms. From 10 to 20 days after the exposure, 7 (87.5%) of the 8 individuals developed abnormal symptoms including fever, malaise, loss of appetite, myalgia, arthralgia, chest pain and dry cough. Five (62.5%) had nodular infiltrative shadows with or without hilar lymphadenopathy in the chest roentgenograms. Eight (100%) of the individuals showed serologic evidence of histoplasmosis. Despite the small number of subjects, this high rate of infection may be related to the fact that the subjects stayed in an enclosed area where air exchange was minimal, at the end of a deep cave infested with numerous bats. The cave involved has never been documented as being endemic for histoplasmosis. The threat of H. capsulatum infection in bat-inhabited caves should be emphasized to travelers and also to physicians.