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Caves Are a Source of Histoplasmosis

In July 1994, acute cave fever (histoplasmosis) developed in several persons who had attended a national meeting in Texas for spelunkers. This development prompted a study to define rates of infection and risk factors for histoplasmosis among attendees.

Among about 620 convention participants offered excursions to 19 different caves, 24 confirmed or suspected cases of acute histoplasmosis were identified. A case-control study identified two caves that were significantly associated with acute histoplasmosis (odds ratios, 13.3 and 12.9). The attack rate was 75% (12 of 16) for those exploring cave A and 71% (10 of 13) for cave B. Although all cavers were previously healthy, they developed fever, chills, headache, and cough 10 to 14 days after exposure. Symptoms continued for 12 weeks in three patients. A cohort study of cavers entering these two caves found that risk factors for acute histoplasmosis included younger age, fewer years of caving, and longer time spent in caves. Of 113 cavers from Texas surveyed separately, 60% had a positive skin test to histoplasmin. Males and cavers with more years of experience were more likely to be positive.

Comment: Health care providers should be aware of the association between caving and histoplasmosis. Persons with underlying conditions such as HIV infection, who are at high risk for severe histoplasmosis, should be counseled about risks of cave exploration. Whether masks would reduce the risk for inhaling the 1- to 2-micron Histoplasma capsulatum spores is unknown, but the question merits study.

— M Wilson

Published in Journal Watch Infectious Diseases August 1, 1999

Citation(s):

Ashford DA et al. Outbreak of histoplasmosis among cavers attending the National Speleological Society annual convention, Texas, 1994. Am J Trop Med Hyg 1999 Jun 60 899-903.

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