This rare fungal disease is becoming more widespread

By Claire Wolters | Fact-checked by Davi Sherman
Published February 1, 2024

Key Takeaways

  • A new study reveals that the rare fungal disease blastomycosis may be more widespread than previously thought.

  • Only about 50% of people infected with the fungus are symptomatic. Symptoms of blastomycosis are similar to those of lung infections, but skin issues, such as lesions or blisters, can also appear. 

  • Individuals who live in areas where the fungus is endemic and who are exposed to plant matter or soil are most at risk.

The rare fungal disease blastomycosis may be more widespread than previously thought, according to a new study published in Emerging Infectious Diseases, a journal from the CDC, on January 24, 2024.[]

What is blastomycosis?

Blastomycosis is a rare and at times fatal disease caused by the fungus Blastomyces, which is found in moist soil and decaying organic matter. Blastomycosis can manifest as pneumonia-like symptoms that can put a person at risk of death, and it can be contracted by breathing in the fungus.[]

The death rate from blastomycosis is between 4% and 22%, according to the study.[] However, not all people who breathe in Blastomyces will contract the disease or be at risk for death. 

So far, blastomycosis has been thought to be endemic in some areas of the United States that border the Ohio and Mississippi Rivers, the Great Lakes, and the St. Lawrence Seaway. As a result, public health surveillance of the fungal disease has been limited to Arkansas, Louisiana, Minnesota, Michigan, and Wisconsin—states considered to be impacted.

The new study reveals, however, that blastomycosis also has a noteworthy presence in Vermont, with higher annual infection rates than some of the endemic areas.[]

Researchers say their findings suggest “the burden of endemic blastomycosis is greater than commonly appreciated,” and that they “challenge routine assumptions about the epidemiology and ecology of this disease and reflect a need for future studies.”[]

What the study found

The study identified 114 Vermont patients with the disease, 34 of whom were hospitalized with the condition during the study period. Four associated deaths were also reported.

These numbers translate to an average annual blastomycosis incident rate of 1.8 patients per 100,000 people in Vermont. This incidence rate is higher than the average annual incidences of the disease in Missouri, Mississippi, and Illinois—three states under surveillance for blastomycosis—based on reports from 1979 to 2018. 

The researchers note that there are inconsistencies in surveillance methods and terminology among states, which make “direct comparisons difficult.”

They write, however, that “Vermont’s burden of blastomycosis appears comparable to, and perhaps higher than, most states that have published blastomycosis incidences.”

Treatment for blastomycosis

Not everyone who gets infected with Blastomyces will become symptomatic. According to the CDC, about half of people who are infected with the fungus experience symptoms.[] When symptoms do occur, they can take about 3 weeks to 3 months to appear. Many symptoms are similar to those of lung infections, like fever, shortness of breath, fatigue, and cough. Other symptoms, including skin lesions, raised bumps, blisters, or ulcers, may appear as well.

The CDC recommends testing a patient for blastomycosis if they are experiencing pneumonia-like symptoms, if they have been given antibiotics that are not working, and if they have been to an area where the fungus lives in the last 3 weeks to 3 months.

It is unclear if these guidelines will change in the aftermath of the study.

“Those who live in endemic areas and participate in activities that may expose them to this fungus, such as those who are exposed to plant matter or soil, are primarily at risk,” Lauren Thayer, RN, a registered nurse with Healthcanal, tells MDLinx.

Thayer recommends that those worried about contracting the disease wear high-quality masks, such as an N95, when visiting at-risk areas or working with patients.

First-line treatment for the condition is an antifungal medication such as Amphotericin B.

What this means for you

A recent study reveals that blastomycosis, a rare fungal disease, may be present in more areas than previously thought. Staying up to date on research and talking to patients about their travel history may help with diagnosis and treatment for this condition.

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