North American blastomycosis; Blastomycosis
Blastomycosis is a rare fungal infection caused by inhaling a fungus (Blastomyces dermatitidis), which is found in wood and soil.
Causes, incidence, and risk factors
Blastomycosis occurs most often in people living in the south-central and midwestern US and Canada. Exposure to soil is the key risk factor. The disease usually affects people with compromised immune systems, such as people with HIV or organ transplant recipients.
Men are more likely to be affected than women. Lung infection may produce no symptoms, but when the infection is widespread, skin lesions or bone lesions may appear and the urogenital system (bladder, kidney, prostate, testes) may be affected.
The incidence of blastomycosis is 1-2 out of every 100,000 people in geographic areas where blastomycosis occurs most frequently. It is even less common outside those areas.
- Cough (the sputum may be brown or bloody)
- Shortness of breath
- General discomfort, uneasiness, or ill-feeling (malaise)
- Unintentional weight loss
- Joint stiffness and joint pain
- Muscular stiffness and pain
- Skin lesions
- Chest pain
Signs and tests
- History of residence in relevant geographical area
- Chest x-ray (may show nodules or pneumonia with cavities)
- Tissue biopsy
- Skin biopsy
- Sputum culture and special stains
Though not all blastomycosis infection in the lungs requires antibiotics, when the disease has spread outside of the lungs or become severe in the lungs, amphotericin B, itraconazole, or other antifungal agents may be prescribed. Periodic follow-up is recommended to detect any recurrence of the disease.
Patients with limited skin lesions and relatively mild lung involvement usually recover completely. Untreated, more severe disease is progressive and can lead to death.
- Large abscesses
- Relapse or disease recurrence
- Unpleasant side effects to drugs such as amphotericin B
Calling your health care provider
Call your health care provider if symptoms suggesting blastomycosis occur.
Avoiding travel to areas where the disorder occurs will prevent exposure, but this is not practical for most people. Although other prevention is unknown, the disorder is rare except in people who are immunosuppressed.
by Simon D. Mitin, M.D.