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Bat-associated histoplasmosis in returning travelers: case presentation and description of a cluster
1University Hospitals of Cleveland, Department of Internal Medicine, Division of Infectious Diseases and Case Western Reserve University, Cleveland, Ohio, USA.
Abstract:
Histoplasma capsulatum is a dimorphic fungus with the mycelial form producing spores that are readily airborne and able to reach small bronchi and alveoli. Isolation of the mycelial form of H. capsulatum in nature shows a striking correlation with moist, acidic soils, frequently contaminated with bird or bat excreta. Bats, but not birds, may be infected by H. capsulatum and may excrete the fungus in their feces. Skin test surveys show that the infectious agent is present worldwide in the areas between 45 degrees north and 30 degrees south of the equator. Clusters of cases may occur because of the disturbance of soil contaminated with H. capsulatum, or by visiting bat caves. Cave-associated histoplasmosis has been reported from the Americas, Africa, Oceania, and Africa. Recently, cave-associated histoplasmosis has been reported in travelers returning from Costa Rica and Peru. We report a cluster of cave-associated acute histoplasmosis that occurred in college students returning from Ecuador. Advice regarding histoplasmosis prevention should be given to travelers planning to visit bat-infested caves, and histoplasmosis should be considered in the differential diagnosis of febrile illness in returning travelers with a history of epidemiologic or geographic exposure.
Insights
Histoplasma capsulatum, a fungus found in soil, causes histoplasmosis. This report details a cluster of acute cases in students returning from Ecuador, highlighting risks for travelers.
Area of Science:
- Mycology
- Infectious Diseases
- Environmental Health
Background:
- Histoplasma capsulatum is a dimorphic fungus found in moist, acidic soils, often linked to bat or bird excreta.
- The fungus's airborne spores can reach the alveoli, causing histoplasmosis, a globally distributed infection.
- Bats are identified as a reservoir for Histoplasma capsulatum, excreting the fungus in their feces.
Observation:
- Cave-associated histoplasmosis outbreaks have been documented across continents, including recent cases in travelers from Costa Rica and Peru.
- A cluster of acute histoplasmosis was identified in college students who had visited Ecuador.
- Soil disturbance and visits to bat-inhabited caves are common risk factors for Histoplasma capsulatum exposure.
Findings:
- The study reports a cluster of acute cave-associated histoplasmosis in students returning from Ecuador.
- Histoplasma capsulatum spores are airborne and pose a risk upon inhalation.
- Geographic and epidemiological exposure, particularly to bat-associated environments, is crucial for diagnosis.
Implications:
- Travelers visiting bat-infested caves should receive preventive advice regarding histoplasmosis.
- Histoplasmosis should be considered in the differential diagnosis of febrile illnesses in returning travelers with relevant exposure history.
- Understanding environmental correlations aids in predicting and preventing Histoplasma capsulatum outbreaks.