Nearly 100 people have likely contracted blastomycosis in an outbreak at the Billerud Paper Mill in Escanaba, Michigan, according to numerous reports and a press release from Public Health Delta & Menominee Counties (PHDM).

Blastomycosis is an infection caused by a fungus called Blastomyces, per the Centers for Disease Control and Prevention (CDC). 

As of April 10, there were 19 confirmed cases and 74 probable cases among employees of the paper mill, per the press release.

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Health agencies are still working to identify the source of the exposure. The fungus thrives in moist soil and decomposing wood and leaves, according to the CDC.

About a dozen of the mill’s employees have been hospitalized, as local outlets reported.

The PHDM was first notified of several pneumonia infections among mill employees on Feb. 28, with the first symptoms beginning in January and February.

On March 3, Billerud learned of the infections from the PHDM. 

Billerud paper mill

The Billerud Paper Mill in Michigan is operated by Billerud AB, an American subsidiary of the Swedish pulp and paper manufacturer (headquarters in Solna, Sweden, are pictured).  (iStock)

"Early testing has indicated that these infections may be caused by a fungal infection called blastomycosis," the PHDM stated in the press release. "Additional testing to confirm these results may take a couple of weeks and is underway."

It can take anywhere from three weeks to three months for symptoms to appear after exposure to the fungus, per the CDC.

Over 10% of mill employees could be infected

The Billerud Paper Mill began operations in 1911. It employs 885 people, nearly 100 of which could be infected with blastomycosis.

The mill produces up to 730,000 tons of paper per year, according to a fact sheet on its website.

It can take anywhere from three weeks to three months for symptoms to appear.

The facility is located in Escanaba, a small community in Delta County in Michigan’s Upper Peninsula.

"The health and safety of our employees, including those who support and visit our mills, is always our first priority," said Brian Peterson, the mill’s vice president, in a statement provided to Fox News Digital.

"From the moment we became aware, we have been leveraging all available public health resources and other professionals to quickly understand any and all measures we can take to support our colleagues and implement proactive steps toward prevention," he went on.

Woman at factory

As of April 7, there were 19 confirmed cases and 74 probable cases among paper mill employees (not pictured). "The health and safety of our Escanaba employees is our first priority," said the mill’s vice president in a statement. (iStock)

Peterson confirmed to Fox News Digital that Billerud has provided its employees with N95 masks, hired an "industrial hygienist" for guidance, deep-cleaned high-traffic areas throughout the mill and inspected ventilation systems and replaced filters.

Local and national health agencies investigating the outbreak include PHDM, the Michigan Department of Health and Human Services, the CDC and the National Institute for Occupational Safety and Health.

Mike Snyder, health officer for Public Health Delta & Menominee Counties, told Fox News Digital that because this is an ongoing investigation, the agency is not making any statements at this time, aside from its weekly press releases.

What to know about blastomycosis

The Blastomyces fungus is found in the midwestern, south-central and southeastern U.S., predominantly in the Ohio and Mississippi River valleys, the Saint Lawrence River and the Great Lakes, per the CDC.

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People can contract blastomycosis by breathing in "microscopic fungal spores," the CDC states on its website.

For most people, the fungus does not cause illness. 

Some, however, will develop symptoms including fever, cough, night sweats, chest pain, fatigue, joint pain, muscle aches or weight loss.

Blastomycosis does not spread from person to person.

Those with compromised immune systems face a higher risk of the infection spreading into their skin, bones, joints and central nervous system, per the CDC.

"Blastomycosis does not spread from person to person or between animals and people," stated the press release from PHDM.

Soil excavation

Outbreaks of blastomycosis have been reported after people engage in construction, excavation or other activities that disturb the natural habitat of the fungi, said medical toxicologist Dr. Kelly Johnson-Arbor. (iStock)

Dr. Kelly Johnson-Arbor, medical toxicologist and co-medical director of the National Capital Poison Center in Washington, D.C., said that because Blastomyces live in the soil, outbreaks of blastomycosis have been reported after people engage in construction, excavation or other activities that disturb the natural habitat of the fungi. 

There is not currently a vaccine for blastomycosis.

"As long as humans continue to engage in deforestation for the expansion of civilization, it’s likely that we will continue to experience outbreaks of blastomycosis in the United States," she told Fox News Digital.

Prevention and treatment

There is not currently a vaccine for blastomycosis.

If a person has a job that involves disturbing soil and develops symptoms of the infection, the CDC recommends seeing a health care provider for early diagnosis and treatment with prescription antifungal medication. 

Additionally, the CDC says any infected employees should contact their employers’ occupational health, infection control, risk management or safety/security department.

Paper mill

The Blastomyces fungus thrives in moist soil and decomposing wood and leaves, according to the CDC. (iStock)

Because the fungus that causes blastomycosis is common in the environment of some areas, limiting exposure can be difficult. 

Those who have weakened immune systems may want to avoid areas where the soil is disrupted, the CDC says.

The PHDM recommends wearing personal protective equipment, including face masks or respirators, eye protection and gloves, to reduce the risk of inhaling the fungal spores when working in areas where soil may be disturbed.

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Additionally, the agency recommends avoiding moving or digging soil on windy days, only moving leaf litter when it is dry, covering soil and yard materials, ensuring adequate drainage of water, and installing walkways over wet areas to avoid walking through muddy soil, as stated in its press release.

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Peterson, Billerud's VP of operations, said the mill's operations are running uninterrupted and that they are continuing to service customers.

"Billerud is continuing to monitor cases to protect the health and safety of our employees, contractors and visitors," he said. 

"We will continue to closely communicate with local union leaders, mill workers, state and local public health officials, and our communities as we learn new information."

This article has been updated with additional information.