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, especially if the infection spreads from the lungs to other organs.

Overview

Blastomycosis is an infection caused by the fungus Blastomyces. The fungus lives in the environment, particularly in moist soil and in decomposing organic matter such as wood and leaves. In the United States, Blastomyces mainly lives in the midwestern, south-central, and southeastern states, particularly in areas surrounding the Ohio and Mississippi River valleys, the Great Lakes, and the Saint Lawrence River. The fungus also lives in Canada, and a few blastomycosis cases have been reported from Africa and India.

People can get blastomycosis after breathing in the microscopic fungal spores from the air, often after participating in activities that disturb the soil. Although most people who breathe in the spores don’t get sick, some of those who do may have flu-like symptoms. In some people, such as those who have weakened immune systems, the infection can become severe, especially if it spreads from the lungs to other organs.

Approximately half of people who are infected with the fungus Blastomyces will show symptoms. The symptoms of blastomycosis are often similar to the symptoms of flu or other lung infections, and can include:

• Fever
• Cough
• Night sweats
• Muscle aches or joint pain
• Weight loss
• Chest pain
• Fatigue (extreme tiredness)

How soon do the symptoms of blastomycosis appear?

Symptoms of blastomycosis usually appear between 3 weeks and 3 months after a person breathes in the fungal spores.

Severe blastomycosis

In some people, particularly those who have weakened immune systems, blastomycosis can spread from the lungs to other parts of the body, such as the skin, bones and joints, and the central nervous system (the brain and spinal cord).

Who gets blastomycosis?

Anyone can get blastomycosis if they’ve been in an area where Blastomyces lives in the environment. People who participate in outdoor activities that expose them to wooded areas (such as forestry work, hunting, and camping) in these areas may be at higher risk for getting blastomycosis. People who have weakened immune systems may be more likely to develop severe blastomycosis than people who are otherwise healthy.

Is blastomycosis contagious?

No. Blastomycosis can’t spread between people or between people and animals.

Can my pets get blastomycosis?

Yes. Pets, particularly dogs, can get blastomycosis, but it is not contagious between animals and people.The symptoms of blastomycosisin animals are similar to the symptoms in humans. If you are concerned about your pet’s risk of getting blastomycosis or if you think that your pet has blastomycosis, please talk to a veterinarian.

How can I prevent blastomycosis?

There is no vaccine to prevent blastomycosis, and it may not be possible to completely avoid being exposed to the fungus that causes blastomycosis in areas where it is common in the environment. People who have weakened immune systems may want to consider avoiding activities that involve disrupting soil in these areas.

Where does Blastomyces live?

Blastomyces lives in the environment, particularly in moist soil and in decomposing organic matter such as wood and leaves. In the United States, the fungus mainly lives in the midwestern, south-central, and southeastern states, particularly in areas surrounding the Ohio and Mississippi River valleys, the Great Lakes, and the Saint Lawrence River. The fungus also lives in Canada, and a small number of blastomycosis cases have been reported from Africa and India.

Life cycle of Blastomyces

Blastomyces lives in the environment as a mold that produces fungal spores. The spores are too small to see without a microscope. When people or animals breathe in the spores, they are at risk for developing blastomycosis. After the spores enter the lungs, the body temperature allows the spores to transform into yeast. The yeast can stay in the lungs or spread through the bloodstream to other parts of the body, such as the skin, bones and joints, organs, and central nervous system (brain and spinal cord).

I’m worried that Blastomyces is in the soil near my home. Can someone test the environment to find out if the fungus is there?

No, in this situation, testing the environment for Blastomyces isn’t likely to be useful. When a soil sample tests positive for Blastomyces, it isn’t necessarily a source of infection, and when a sample tests negative, that doesn’t necessarily mean that the fungus isn’t in the soil. Also, there are no commercially-available tests to detect Blastomyces in the environment. Testing environmental samples for Blastomyces is currently only done for scientific research.

How is blastomycosis diagnosed?

Healthcare providers use your medical and travel history, symptoms, physical examinations, and laboratory tests to diagnose blastomycosis. A doctor will likely test for blastomycosis by taking a blood sample or a urine sample and sending it to a laboratory.

Healthcare providers may do imaging tests such as chest x-rays or CT scans of your lungs. They may also collect a sample of fluid from your respiratory tract or perform a tissue biopsy, in which a small sample of affected tissue is taken from the body and examined under a microscope. Laboratories may also see if Blastomyces will grow from body fluids or tissues (this is called a culture).

Where can I get tested for blastomycosis?

Most healthcare providers can order a test for blastomycosis.

How long will it take to get my test results?

It depends on the type of test. Results from a blood test or a urine test are usually available in a few days. If your healthcare provider sends a sample to a laboratory to be cultured, the results could take a couple of weeks.

How is blastomycosis treated?

Most people with blastomycosis will need treatment with prescription antifungal medication. Itraconazole is a type of antifungal medication that is typically used to treat mild to moderate blastomycosis. Amphotericin B is usually recommended for severe blastomycosis in the lungs or infections that have spread to other parts of the body. Depending on the severity of the infection and the person’s immune status, the course of treatment can range from six months to one year.