Infants, young children, and older persons, in particular those with chronic lung disease are at increased risk for severe disease. H. capsulatum grows in soil and material contaminated with bat or bird droppings. Spores become airborne when contaminated soil is disturbed. Breathing the spores causes infection. The disease is not transmitted from an infected person to someone else.
Most infected persons have no apparent ill effects.
The acute respiratory disease is characterized by respiratory symptoms, a general ill feeling, fever, chest pains, and a dry or nonproductive cough. Distinct patterns may be seen on a chest x-ray. Chronic lung disease resembles tuberculosis and can worsen over months or years. The disseminated form is fatal unless treated. Antifungal medications are used to treat severe cases of acute histoplasmosis and all cases of chronic and disseminated disease.