Blastomycosis is an uncommon infection of humans, dogs, cats, and other animals. It is caused by a fungus (Blastomyces dermatitidis) found in moist, organically rich soil. It has been present for many years, but it is increasingly recognized in north central Wisconsin. It is most commonly an infection of the lungs, but can also affect other internal organs, bones, joints, or skin.

How Do People Get Blastomycosis

Blastomycosis is almost always acquired by inhaling spores of the fungus. Rarely, it can be acquired directly through the skin. Since this fungus grows in the soil, construction, digging, or gardening may cause the fungal spores to be released into the air and inhaled. You can only get blastomycosis from the fungus in the soil or the spores in the air. You cannot get it from another person or an animal.

Who is at Risk

Blastomycosis can affect anyone, but it is actually a very uncommon disease. Most healthy people are resistant to it. It occurs more in men than women, probably reflecting differences in occupational and recreational choices. Adults are more commonly affected than children. The risk may be higher for farmers, construction workers, hunters, campers, and others who are often exposed to moist soil with rotting leaves and wood. Blastomycosis can be more severe in persons with a weakened immune system (such as organ transplant recipients, those on steroids or chemotherapy, people with HIV) and those with diabetes.

What are the Symptoms of Blastomycosis

Blastomycosis may seem like the "flu", with cough, muscle aches, joint pain, fatigue, shortness of breath, chills, and fever. Symptoms are usually similar to those of other kinds of pneumonia. In our area, blastomycosis should be considered in anyone with pneumonia that does not improve on usual antibiotic treatment. Blastomycosis symptoms may develop suddenly, or days to weeks after exposure to the fungus. In some people the symptoms go away naturally, but others may develop persistent and progressive symptoms. Since the infection can spread to other parts of the body, the symptoms can be quite varied, reflecting the areas affected.

How is Blastomycosis Diagnosed

The diagnosis may be suspected from clues in the physical examination and chest x-ray; but proof requires identification of the fungus under the microscope. The laboratory can identify the fungus in sputum, pus, or other specimens. Special procedures, such as a bronchoscopy, are sometimes required to obtain satisfactory specimens. There are no blood tests that are reliable.

How is Blastomycosis Treated

Blastomycosis can be successfully treated with antifungal drugs, usually taken orally. Severe cases may require hospitalization for intravenous medications. Treatment is usually given for months. Regular clinic follow-up visits are necessary to monitor progress and watch for treatment side effects.

How can I Avoid Blastomycosis

Even if you work, live, or vacation in the areas where the fungus grows, it is important to remember that blastomycosis is a rare condition and the risk of getting it is very low. Testing soil for the presence of this fungus is very difficult and not very reliable. If you do come in contact with the fungus, it does not mean you will get an infection. Therefore, it is not necessary for people to avoid any specific areas. Little is known about the actual fungal locations at any particular time, or the conditions that cause the fungus to grow or die in the soil. If your immune system is weakened, you may wish to avoid activities that require working in the soil. There is no vaccine for blastomycosis.

When working in moist soil areas where the fungus may grow; such as under the house, cottage, porch, or shed, wear:

  • Work gloves

  • Proper footwear

  • Long pants

  • Long-sleeved shirt

  • Disposable dust mask (NIOSH approved HEPA filter)

This may help to prevent blastomycosis.