Blastomycosis is an infection, mainly of the lungs, caused by the fungus Blastomyces.
The infection is caused by inhaling spores of the fungus.
People have a fever, chills, and drenching sweats and sometimes chest pain, difficulty breathing, and a cough.
The infection may spread to the skin, bones, reproductive and urinary tracts, and tissues covering the brain, causing swelling, pain, and other symptoms.
A sample of infected sputum or tissues is removed and sent for culture, and a chest x-ray is taken.
Antifungal medications can eliminate the infection.
(See also Overview of Fungal Infections.)
Blastomycosis is a rare infection. It mostly affects adult males, possibly because males are more likely to work or play in areas where the fungus is common, such as in moist soil that contains dead or decaying plants, leaves, and animal remains and animal feces.
Most cases of blastomycosis occur in areas of North America where the fungus lives in the soil near rivers:
The Ohio and Mississippi River Valleys (extending into the middle Atlantic and southeastern states)
The northern Midwest
Upstate New York (Mohawk River Valley)
Areas of southern Canada that border the Great Lakes and Saint Lawrence River
Rarely, the infection occurs in the Middle East and Africa.
Blastomyces reproduce by spreading microscopic spores. The Blastomyces spores 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, most commonly the skin. Once in the lungs, blastomycosis can also spread to the prostate gland, epididymides, testes, seminal vesicles, kidneys, vertebrae, ends of long bones, the deepest layer of the skin, central nervous system, the membranes lining the mouth or nose, thyroid gland, lymph nodes, and bone marrow.
Blastomycosis can occur in people who have a healthy immune system. However, it may be more common among and more severe in some people with a weakened immune system. Unlike most fungal infections, blastomycosis is not more common among people with advanced HIV infection (also called AIDS). However, it tends to be more severe in people with advanced HIV infection.
Symptoms of Blastomycosis
Sometimes blastomycosis of the lungs causes no symptoms or causes symptoms that disappear quickly and are not recognized.
When symptoms do occur, they can begin abruptly or gradually. They include a fever, chills, and drenching sweats.
Chest pain, difficulty breathing, and a hacking cough that may or may not bring up sputum may also develop. The lung infection usually progresses slowly, and people sometimes get better without treatment.
In some people, infection progresses rapidly.
When blastomycosis spreads from the lungs, it can affect many areas of the body, but the most common sites are the following:
Skin
Bones
Reproductive and urinary tracts (including the prostate gland)
Brain and the tissues that cover it
Infection that spreads to the skin begins as very small, raised bumps (papules), which may contain pus. Raised, wart-like patches then develop, surrounded by tiny, painless collections of pus (abscesses).
In blastomycosis, infection that spreads to the skin begins as very small, raised bumps. This photo shows a blister.
Image courtesy of www.doctorfungus.org © 2005.
Tissues over infected bones may become swollen, warm, and tender.
In men, the coiled tube on top of a testis (epididymis) may swell, causing pain, or infection of the prostate gland (prostatitis) may cause discomfort. In women, genital problems are less common, but blastomycosis can cause an abscess (a pocket of pus) to form in the ovaries and fallopian tubes, an infection in the lining of the uterus, and an infection of the fallopian tubes.
Fungi can spread to the tissues that cover the brain and spinal cord (meninges), causing fungal meningitis. Abscesses may develop in the brain. People may have headache and confusion.
Diagnosis of Blastomycosis
Examination and culture of a sample of infected material
Chest x-ray
Antigen test
A doctor diagnoses blastomycosis by sending a sample of sputum or infected tissue to a laboratory to be examined under a microscope and cultured.
A chest x-ray is taken to check for signs of infection in the lungs.
Doctors may also do a urine and blood test to look for proteins (antigens) released by the fungus.
Tests that detect genetic material in microorganisms, such as polymerase chain reaction (PCR), can be done. The PCR test is used to produce many copies of a gene from the fungus, making the fungus much easier to identify.
Treatment of Blastomycosis
Antifungal medications
If blastomycosis is severe, amphotericin B is given by vein (intravenously). If blastomycosis is mild to moderate, itraconazole is given by mouth. If blastomycosis is severe, amphotericin B is given by vein (intravenously). If blastomycosis is mild to moderate, itraconazole is given by mouth.
With treatment, people begin to feel better fairly quickly, but itraconazole must be continued for 6 to 12 months or sometimes longer. With treatment, people begin to feel better fairly quickly, but itraconazole must be continued for 6 to 12 months or sometimes longer.
Without treatment, blastomycosis slowly worsens and, rarely, is fatal.
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