ESCANABA, Mich. (From news reports) -- More than 90 employees at an Upper Peninsula paper mill are believed infected with a fungus found in soil and decaying wood, with about a dozen requiring hospitalization.

Investigation of a blastomycosis outbreak at the Billerud paper mill in Escanaba is ongoing, and involves local, state and federal health and occupational safety officials. With nearly 900 employees, the Billerud mill is the largest manufacturing employer and economic driver north of Midland in the state, according to the Michigan Economic Development Corp.

A blastomycosis outbreak affecting large numbers of people is highly unusual, as the fungal disease is not typically transferred from person to person. It indicates that instead, scores of employees were infected from the same materials containing the blastomyces fungal spores, which exist in the environment in the eastern U.S. and parts of Canada.

What the fungus does inside the human body
"I've been at the paper mill for about 11 years, and we have never seen anything like this," said Gerald Kell, president of the United Steel Workers Local 21 union that represents about 670 of the mill's employees.

According to a release Friday from the local health department, Public Health Delta and Menominee Counties, some 19 cases of blastomycosis have been confirmed in Billerud employees through biopsies and/or laboratory cultures, with another 74 workers testing as probable cases -- having symptoms of blastomycosis with a positive antigen or antibody test from urine or saliva.

"Roughly a dozen" employees have been hospitalized "to one degree or another" as a result of the disease, including at least one employee who has required hospitalization for weeks, Kell said.

According to the U.S. Centers for Disease Control and Prevention, people contract blastomycosis after breathing in microscopic fungal spores from the air, often after participating in activities that disturb the soil. Once inside the lungs, the body's warmth and moisture can transform the spores into yeast that can stay in the lungs or be transferred through the bloodstream to other parts of the body, including the skin, bones, joints, organs, brain and spinal cord.

Cases are rare; death is even more unusual
Most people who breathe in the blastomyces spores don't get sick, but some develop symptoms that mimic a cold, the flu or other more common respiratory ailments: fever, cough, night sweats, muscle aches or joint pain, chest pain and extreme fatigue.

In some people, especially those with weakened immune systems, blastomycosis can become serious.

States that track blastomycosis report only about one or two cases per 100,000 population a year. Deaths from the disease are similarly rare, with the CDC finding 1,216 blastomycosis-related deaths occurred in the U.S. from 1990 to 2010.

Kell said symptoms of the infection began in early March.

"We had a few people out with respiratory (symptoms)," he said. "A couple of them were pretty severe; they required hospitalization."

Those early hospitalized workers were treated for bacterial pneumonia, and weren't improving, Kell said. That was when additional testing by medical personnel discovered the blastomycosis.

"It's not something they would typically test for," he said. "Now, people are getting identified quickly, and are getting more effective treatment."

Treatment is with anti-fungal medications, often requiring courses of treatment lasting six months to a year.

In addition to the local health department, investigating agencies at the paper mill include the Michigan Department of Health and Human Services, the federal Centers for Disease Control and Prevention and the National Institute for Occupational Safety and Health.

Source of fungus not yet determined
The Escanaba plant is owned by the American Subsidiary of Billerud AB, a Swedish pulp and paper manufacturer. Company officials referred the Free Press to a statement made by Billerud Escanaba Mill Operations Vice President Brian Peterson.

"The health and safety of our Escanaba employees is our first priority," he said. "Although the source of the infection has not been established, we continue to take this matter very seriously and are following recommendations from health and government officials and implementing numerous, proactive steps to protect the health and safety of our employees, contractors and visitors."

It's not clear whether more workers are contracting the disease, or whether more are exhibiting symptoms from the same exposure, Kell said.

"You and I may be exposed on the same day from the same source, and you might develop symptoms in three or four weeks, and I might in three or four months," he said.

"Of course, people are concerned. We aren't sure where the exposure is coming from. It's not pinpointed; we have cases throughout the mill. It's a 2,200-acre facility."

Workers are being encouraged to wear company-provided N95 masks, and HVAC systems and other areas of the plant are being deep-cleaned as advised by health and occupational safety officials, Kell said.

The community has rallied around the paper mill, with a fundraiser hosted by the union last weekend to offset the expenses of the most seriously ill employees, generating more than $30,000, Kell said.