Blastomycosis: Infection with a fungus called Blastomyces dermatitidis. The infection causes symptoms in about 50% of cases. It usually presents as a flu-like illness with fever, chills, productive cough, myalgia, arthralgia and pleuritic chest pain. Some patients fail to recover and develop chronic pulmonary infection or widespread disseminated infection (affecting the skin, bones, and genitourinary tract). It occasionally affects the meninges which cover the brain and spinal cord.

The offending fungus is found in moist soil enriched with decomposing organic debris. It is endemic in parts of the south-central, south-eastern and mid-western United States and in microfoci in Central and South America and parts of Africa. Transmission of the fungus is by inhalation of airborne conidia (spores) after disturbance of contaminated soil.

Persons at elevated risk for the disease are those in areas with endemic disease with exposures to wooded sites (e.g., farmers, forestry workers, hunters, and campers). People who are immunodeficient are also at higher risk for blastomycosis. The disease can leave permanent lung damage. Mortality (death) rate is about 5%.