Fungal Infection Outbreak: Over 90 Employees At Michigan Paper Mill Fall Ill

More than 90 people have fallen ill with a fungal infection at a paper mill in Michigan. The exact source of the infections is still unclear.

A total of 93 people have been affected in a blastomycosis outbreak at the Escanaba Billerud Paper Mill in Michigan, the Public Health Delta & Menominee Counties (PHDM) noted. Of them, 19 are confirmed cases, while 74 are considered to be "probable cases."

"A confirmed case is a person with symptoms of blastomycosis and where the fungus has either been grown (culture) or seen by microscope in a test specimen," the agency explained. "A probable case is a person with symptoms of blastomycosis and who has a positive antigen or antibody test."

Blastomycosis is an infection that's caused by fungus called Blastomyces. They live in moist soil or decomposing matter. People may get blastomycosis If they inhale the spores of the fungus. The agency clarified that this cannot be passed from one person to another, or from animals to people.

The PHDM learned about the cluster of "atypical pneumonia infections" among employees of the mill on Feb. 28. At the time, only 15 cases were identified, with the patients' symptoms beginning in January and February. The agency said blastomycosis cases are "exceedingly rare."

By March 17, there were 35 confirmed or probable blastomycosis cases and the test results were pending in nine others. It grew to 53 cases (14 confirmed, 39 probable) by March 24, and to 81 cases (19 confirmed, 62 probable) by the end of March.

About a dozen employees have been hospitalized so far, said Gerald Kell, president of the United Steel Workers Local 21 union, which represents hundreds of the mill's employees, Detroit Free Press reported.

The exact source of the infection was not identified, noted Brian Peterson, operations vice president at Escanaba Billerud Paper Mill.

"The health and safety of our Escanaba employees is our first priority," said Peterson. "...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."

Blastomycoses is present mainly in midwestern states, according to the U.S. Centers for Disease Control and Prevention. Just last week, the CDC issued a warning about cases of blastomycosis affecting people and dogs in Wisconsin.

A 2022 study found that lung infections caused by Blastomyces and other such soil fungi may actually be more common in the U.S. than previously thought — they were increasingly diagnosed "outside their historical areas of endemicity."