What to know about blastomycosis

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Blastomycosis is a type of fungal infection that occurs when a person inhales spores of the Blastomyces dermatitidis or Blastomyces gilchristii fungus.

As the fungus tends to live in moist soil and decomposing leaves or wood, a person is most likely to inhale the spores when performing an activity that disrupts the soil, such as:

• digging
• clearing wood
• excavation
• construction

In around 25–30% of people with blastomycosis, the infection will travel from the lungs to another part of the body, most commonly the skin.

Blastomycosis is generally not contagious. This means that it does not usually transmit from a person or an animal to another person.

However, the Centers for Disease Control and Prevention (CDC) notes that, on extremely rare occasions, it may transmit through a needlestick injury, a bite, or sexual contact.

Around 50% of people who develop blastomycosis will experience symptoms. It typically takes anywhere from 3 weeks to 3 months after exposure for symptoms to appear, though they may begin before or after this time.

When symptoms do develop, they can include:

• a cough
• fever
• joint pain
• muscle aches
• night sweats
• chills
• unexplained weight loss
• fatigue
• chest pain
• hemoptysis, or coughing up blood from the respiratory tract
• skin lesions, such as ulcers or blisters

To assist with reaching an accurate diagnosis, a doctor may begin by taking a full medical history, asking questions about symptoms, and performing a physical exam.

As blastomycosis is more prevalent in the South Central, Southeastern, and Midwestern states of the United States, a doctor may also ask questions about a person’s recent travel history.

They may then order various tests to confirm the diagnosis or rule out other possible causes. Tests can include a:

• chest X-ray
• CT scan of the lungs
• tissue biopsy
• collection of fluid from the respiratory tract

For people with mild to moderate cases of blastomycosis, doctors typically recommend the antifungal medication itraconazole.

Doctors may recommend amphotericin B in severe cases or if the infection has spread beyond the lungs to other parts of the body.

According to the CDC, treatment for blastomycosis can range from 6 months to 1 year.

Learn more about antifungal medications.

Blastomycosis affects around 1–2 per 100,000 people each year in states where the condition is most common, including:

• Wisconsin
• Mississippi
• Kentucky
• Arkansas

People also report cases of blastomycosis in the following states:

• North Carolina
• Tennessee
• Louisiana
• Illinois
• Minnesota
• Michigan

People most commonly report the condition in Wisconsin. Some northern counties report an incidence of around 10–40 cases per 100,000 people each year.

It may not be possible to completely prevent blastomycosis.

The CDC recommends that people with a weakened immune system avoid activities that disrupt the soil in areas where the condition is most common.

There are various possible complications of blastomycosis, including:

• spread of the infection to other parts of the body
• abscesses
• skin sores
• bone infections
• central nervous system involvement

Receiving an accurate diagnosis and beginning a suitable treatment plan as early as possible may help reduce the risk of complications.

Here are some frequently asked questions about blastomycosis.

Does blastomycosis go away?

Although blastomycosis may go away on its own, doctors recommend that people with the condition receive medical treatment. This typically includes the antifungal medication itraconazole for mild to moderate cases, or amphotericin B in severe cases.

How fatal is blastomycosis?

A person may be at an increased risk of complications if they have a weakened immune system. People with a weakened immune system should consider avoiding activities that disturb the soil.

A 2020 meta-analysis of people with Blastomyces dermatitidis infection showed an overall pooled mortality rate of 6.6%. Mortality rates increased in people with compromised immune systems.

What is the survival rate of blastomycosis in humans?

Around 80–95% of people with blastomycosis recover from the condition with successful treatment.

Blastomycosis is a type of fungal infection that occurs following exposure to the Blastomyces dermatitidis or Blastomyces gilchristii fungus. A person can develop the condition if they take part in activities that disturb the soil, particularly in parts of the U.S. where the fungus is more common.

Symptoms of blastomycosis include a cough, fever, joint and muscle pain, and more. Doctors typically recommend antifungal medication to treat the condition.

A person should contact a doctor if they suspect they have blastomycosis. The doctor can order various tests to confirm the diagnosis and advise on suitable treatments.