Blastomycosis is a disease caused by the fungus Blastomyces dermatitidis. The fungus lives in moist soil and in association with decomposing organic matter such as wood and leaves. Lung infection can occur after a person inhales airborne, microscopic fungal spores from the environment; however, many people who inhale the spores do not get sick. The symptoms of blastomycosis are similar to flu symptoms, and the infection can sometimes become serious if it is not treated.
Fungal infections pose an increasing threat to public health for several reasons.
Symptoms of Blastomycosis
Only with about half of the people who are infected with blastomycosis will show symptoms. If symptoms occur, they usually appear between 3 and 15 weeks after being exposed to the fungus. The symptoms of blastomycosis are similar to flu symptoms, and include fever, chills, cough, muscle aches, joint pain, and chest pain. In very serious cases of blastomycosis, the fungus can disseminate (spread) to other parts of the body, such as the skin and bones.
Risk & Prevention
Who gets blastomycosis?
Anyone can get blastomycosis, even people who are otherwise healthy. However, people who have underlying medical conditions such as diabetes may be at increased risk for the infection. Blastomyces dermatitidis, the fungus that causes blastomycosis, can be found throughout the world, but is most common in parts of North, Central, and South America. In the United States, the fungus is endemic (native and common) in the Southeast and the Midwest.
People who live in endemic areas and engage in activities that expose them to wooded areas may be at a higher risk for getting blastomycosis. This may include farmers, forestry workers, hunters, and campers.
How can I prevent blastomycosis?
There is no vaccine to prevent blastomycosis. In endemic regions, such as the Mississippi and Ohio River valleys, it may not be possible to completely avoid being exposed to the fungus. However, people who have weakened immune systems may consider avoiding wooded areas where the fungus is prevalent.
Blastomycosis Diagnosis and Testing
There are multiple tests available to diagnose blastomycosis. The best way to diagnose the infection is to perform a fungal culture. Doctors take small samples from tissues or body fluids, such as blood, sputum, bone marrow, liver, or skin and see if the fungus will grow from these samples in a laboratory. Blastomycosis can also be diagnosed by looking at a small sample of infected tissue under a microscope. An antigen test can detect the presence of the fungus in a urine or serum sample, and a blood test can measure prior exposure to the fungus by detecting Blastomyces antibodies.
Treatment and Outcomes for Blastomycosis
Blastomycosis requires treatment with antifungal medicine that must be prescribed by your doctor. For people with mild or moderate infections, itraconazole is commonly used. People with more severe infections may require more aggressive treatment with amphotericin B. Newer triazole antifungal medications, such as voriconazole and posaconazole, are also available, but their role in treating blastomycosis is still being determined.