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Ask the Expert: About blastomycosis

​ Jeffrey Moore, M.D.
​​​​Jeffrey Moore, M.D.​
Family Physician
Sees patients at Marshfield Clinic Merrill Center.

Question: Should I be worried about blastomycosis?​

Aware, yes. Worried, no.

Although blastomycosis is not a th​reat to most healthy people, it is certainly a potentially serious illness. At least two people from the Merrill area have died from this disease. ​

A number of cases have been reported in Lincoln and Marathon counties.

The infectious disease blastomycosis is rare in most areas of the United States but more common in our region. Nationally, about four of 100,000 people will get the disease.

In Lincoln County, the normal rate is 40 per 100,000 and in 2006 the rate spiked to around 100 per 100,000.

Even at that rate, however, other lung diseases and other causes of lung infection are considerably more common.

Blastomycosis is caused by exposure to the fungus Blastomyces dermatitidis, which is believed to reside in organically rich soil and decaying vegetation.

The fungus can release spores into the air. When inhaled, these spores can germinate in the lung and cause symptoms similar to pneumonia, including persistent cough, chest pain, shortness of breath and fever.

In our area, blastomycosis should be considered in anyone with pneumonia that does not improve on the usual antibiotic treatment.

In occasional cases, the fungus can spread from the lungs to other parts of the body. Anyone experiencing those symptoms should seek immediate medical attention.

Most primary care physicians in central Wisconsin are familiar with the diagnosis and treatment of this disease.

We most often see blastomycosis in people who excavate soil, work in construction, hunt or garden, but sporadic cases seem to show up among people who have little or no exposure to the outdoors.

People with immune system problems and certain chronic diseases such as diabetes are at higher risk of infection.

Doctors must diagnose blastomycosis with certainty before beginning treatment. We can do this with a sputum examination; if the fungus is present, it will show up under microscopic examination or fungus culture.

In some cases of blastomycosis, the fungus can be more elusive and more specialized procedures may be required to confirm the suspicion.

We typically treat this disease with oral antifungal medications, which the patient may need to take for six months or more to prevent recurrence. In severe cases, the patient may need to be hospitalized to have the treatment administered intravenously.​


Marshfield Clinic provides family medicine​ services in a number of our centers. Your primary care doctor can refer you to the appropriate specialty and location. ​