Histoplasmosis Facts (cont.)

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What causes histoplasmosis?

The causative organism is a fungus, Histoplasma capsulatum. The fungus is often found in association with bird or bat droppings in the environment. When the microscopic fungal spores are inhaled, some people develop an illness similar to pneumonia. Not everyone who inhales the spores develops the illness. The spores may become airborne in demolition projects in areas that contain bat or bird droppings. The airborne spores can travel hundreds of feet. It has been estimated that in the U.S. around 250,000 people are infected each year.

Histoplasma capsulatum can be found throughout the world, but it is most commonly located in North and Central America. Within the U.S., it is particularly common in the Ohio and Mississippi River valleys. In areas where the fungus is common, between 50%-80% of people will show an antibody response to the organism, meaning that they have been exposed to the fungus at some point in their life.

What are risk factors for histoplasmosis?

Anyone may develop histoplasmosis. However, the illness is more likely to occur in infants, young children, and the elderly. People with suppressed immune function or chronic lung disease are also at increased risk for severe (disseminated) disease. The soil may also become contaminated with the fungus, so those who work with soil, such as landscapers and farmers, are at greater risk. Also at risk are workers performing demolition work in areas that may be contaminated with bird or bat droppings.

What are histoplasmosis symptoms and signs?

As mentioned before, not everyone who inhales the fungal spores becomes sick. When illness does occur, the signs and symptoms appear anywhere from three to 17 days after exposure. The symptoms are similar to pneumonia and include fever, chills, sweats, a dry cough, malaise, and chest pains. Some affected people also experience joint pains.

If these disease progresses without treatment, those affected may develop weight loss, shortness of breath, and fatigue. Ocular involvement in disseminated disease can cause loss of vision. If the infection spreads to the central nervous system, severe symptoms including seizures, headaches, and confusion may develop.

Medically Reviewed by a Doctor on 6/3/2014

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