Blastomycosis (North American blastomycosis, Gilchrist's disease) is infection, mainly of the lungs, caused by the fungus Blastomyces dermatitidis.
Spores of Blastomyces probably enter the body through the airways when the spores are inhaled. Thus, blastomycosis affects primarily the lungs, but the fungi occasionally spread through the bloodstream to other areas of the body, including the skin.
Most infections occur in the United States, chiefly in the Southeast and the Mississippi River valley, where the fungus lives in the soil near river beds. Infections have also occurred in widely scattered areas of Africa. Men aged 20 to 40 years are most commonly infected. Unlike most fungal infections, blastomycosis is not more common among people with AIDS.
Blastomycosis of the lungs begins gradually with a fever, chills, and drenching sweats. Chest pain, difficulty breathing, and a cough that may or may not bring up sputum may also develop. The lung infection usually progresses slowly, but people sometimes get better without treatment.
When blastomycosis spreads, it can affect many areas of the body, but the skin, bones, and reproductive and urinary tracts (including the prostate gland) are the most common sites. Skin infection begins as very small, raised bumps (papules), which may contain pus. Raised, warty patches then develop, surrounded by tiny, painless collections of pus (abscesses). Tissues over infected bones may become swollen and painful. In men, the coiled tube on top of testes (epididymis) may swell, causing pain, or infection of the prostate gland (prostatitis) may cause discomfort.
Occasionally, fungi spread to the tissues that cover the brain and spinal cord (meninges), causing fungal meningitis. This infection can cause headache and confusion.
Diagnosis and Treatment
A doctor diagnoses blastomycosis by sending a sample of sputum or infected tissue to a laboratory to be examined under a microscope and cultured.
Blastomycosis may be treated with amphotericin B, given intravenously, or itraconazole or voriconazole, given by mouth. With treatment, people begin to feel better fairly quickly, but the drug must be continued for months. Without treatment, blastomycosis slowly worsens and leads to death.
Last full review/revision October 2008 by Alan M. Sugar, MD