A fungal outbreak in Michigan has caused one death and over 100 illnesses

By Lisa Marie Basile | Fact-checked by Davi Sherman
Published May 2, 2023

Key Takeaways

  • An outbreak of blastomycosis at a Michigan paper mill has left one dead and 109 others sick. Thirteen people have been hospitalized.

  • Blastomycosis is caused by a geographic fungus called Blastomyces, predominantly found in the midwestern, south-central, and southeastern states. 

  • Fifty percent of infections are asymptomatic, but the illness can lead to fever, chest pain, a bloody cough, fatigue, weight loss, night sweats, and skin lesions. Experts recommend physicians be aware of potential fungal infections when diagnosing patients.

One person died—and 109 others became ill—after an outbreak of blastomycosis at the Billerud Paper Mill in Escanaba, MI, last month. As of April 28, 13 of the 109 people—including the mill’s employees, contractors, and visitors—who became sick were hospitalized, according to a local public health department statement.[]

“Blastomycosis is an infection caused by a type of endemic, or geographic, fungus—Blastomyces. These are fungal infections that are generally contained to a certain geography,” explains Dr. Luis Ostrosky-Zeichner, MD, Division Chief of Infectious Diseases of the McGovern Medical School (a part of UTHealth) and Chief Epidemiology Officer for Memorial Hermann Health System. 

It’s not surprising that this particular fungus was found at the Michigan mill, as “blastomycosis is known to be very prevalent in the midwest,” Ostrosky-Zeichner notes. The fungus is also found in the south-central and southeastern states, according to the Centers for Disease Control & Prevention (CDC).[] That said, getting sick from Blastomyces isn’t common. Data from 2019 show only 240 reported cases of blastomycosis.[]

According to an April 13 press release published on Billerud’s website, the mill first found out about the fungus on March 3 after being contacted by Public Health, Delta & Menominee Counties (PHDM), the local health department in Escanaba, MI. Several of the mill’s employees were hospitalized due to “atypical pneumonia infections.”[]

The same press release also said that the outbreak led to a “temporary idling” of the mill for up to three weeks to “protect the health and safety of its employees and contractors.” The mill will be properly cleaned based on recommendations from the National Institute for Occupational Safety & Health (NIOSH) and other organizations.[] 

The NIOSH made several initial recommendations for the mill, which included:[]

  • Voluntary use of N95® disposable filtering-facepiece respirators by employees, especially those at risk for serious illness.

  • Inspections of the heating, ventilation, and air conditioning systems.

  • Working with a “licensed ventilation engineer or building scientist to inspect ductwork for water incursion or microbial growth.”

  • Limiting disruptions to soil, as the fungus is able to grow in moist soil, wood, and leaves.

  • Encouraging employees with symptoms to seek care.

 “Although the source of the infection has not been established, and we have not received any information from the mill’s investigation, public health officials, or any of the organizations assisting in this investigation, that indicates visiting or working at the mill is unsafe, we take this matter very seriously,” the April 13 press release said.[]

Additionally, the release stated, “Identifying the source can be difficult because the blastomyces fungus is endemic to the area and there has never been an industrial outbreak of this nature documented anywhere in the U.S.” 

A late April visit by NIOSH is planned in order to clarify next steps.[]

A closer look at blastomycosis

Blastomyces—a mold that produces fungal spores—lives in “moist soil and in decomposing organic matter such as wood and leaves,” says the CDC. When soil or organic matter are disturbed, spores can be released into the air and breathed in. When spores enter the lungs, they are transformed into yeast within the body.[] 

Most people won’t actually get sick when they breathe in the spores. “For the most part,” Ostrosky-Zeichner says, “if your immune system is okay, you might not even know you have it. Or, you might have an infection in your lungs. If you have a large dose of spores or if you're immunocompromised, [sickness] may be [more severe] for you. It can go from the lungs to other parts of the body.” []

In fact, half of people with blastomycosis will be asymptomatic, says the CDC, while those who get sick may see symptoms appear anywhere from three weeks to three months after initial exposure.[] 

Blastomycosis is not contagious and cannot be spread from person to person through the air, although in rare cases, it has been spread through needlestick injuries, bites, or sexual contact. Symptoms can include fever, chest pain, cough (with blood), fatigue, weight loss, night sweats, and skin lesions.[]

Fungus should be top of mind for physicians

Ostrosky-Zeichner says that while viral and bacterial diseases often get the most attention, physicians—especially those in the emergency room—should be aware of geographic mycose.[] 

A big reason for this? There are more fungal infections these days, potentially due to climate change. It wasn’t always this way, though. “Fungus was the black sheep of microbiology,” Ostrosky-Zeichner says. “It was the last topic you'd be taught. It was rare. But today, we’re seeing a literal explosion of fungal infections.” In fact, an article in PLOS Pathogens found that blastomyces is one of the various soil-borne fungal pathogens “speculated to have increased in frequency or range due to climate-induced disruptions.”[] 

The journal goes on to state that, “Outside of their normal range, these fungal infections can be challenging to diagnose and they are often refractory to treatment, frequently resulting in poor patient outcomes.” 

Ostrosky-Zeichner offers a few insights for physicians who may suspect a fungal infection: “Diagnosis will start with clinical suspicion.” “Blastomycosis may look like atypical pneumonia. There may be skin lesions. Physicians should confirm with imaging, serological testing, or testing for antibodies.”

“If a patient doesn't meet the criteria for a bacterial infection or when a patient doesn’t get better on antibiotics, consider a fungal infection,” Ostrosky-Zeichner adds. Patients with blastomycosis should be treated with antifungal medications, such as itraconazole.

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