Blastomycosis is an infection, mainly of the lungs, caused by the fungus Blastomyces dermatitidis.
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 must be taken for months.
(See also Overview of Fungal Infections.)
Spores of Blastomyces 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 normal 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 AIDS. However, it tends to be more severe in people with AIDS.
Most cases of blastomycosis occur in areas of North America where the fungus lives in the soil near river beds:
The Ohio and Mississippi River valleys (extending into the middle Atlantic and southeastern states)
The northern Midwest
Upstate New York
Areas of southern Canada that border the Great Lakes and Saint Lawrence River
Rarely, the infection occurs in the Middle East or Africa.
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, but 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
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).
Image courtesy of www.doctorfungus.org © 2005.
Tissues over infected bones may become swollen, warm, and painful.
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. This infection can cause headache and confusion.
Diagnosis of Blastomycosis
Examination and culture of a sample of infected material
Chest x-ray
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 a microorganism, making the microorganism much easier to identify.
Treatment of Blastomycosis
Antifungal medications
With treatment, people begin to feel better fairly quickly, but the medications must be continued for 6 to 12 months or sometimes longer. Without treatment, blastomycosis slowly worsens and, rarely, is fatal.
