Industrial Outbreak of Blastomycosis at Michigan Paper Mill

Industrial Outbreak of Blastomycosis at Paper Mill

Natalie Johnson
Posted 04/19/2023

An industrial outbreak of blastomycosis is being investigated at a paper and packaging mill in Escanaba, Michigan. This is the first fungal outbreak of its kind in the history of the United States and the mill has decided to temporarily halt operations to ensure the health and safety of workers.

The mill, local and federal authorities, and an industrial hygienist will be aiding in the investigation and performing maintenance to ensure the 2,000 acre facility is thoroughly cleaned and ventilated to prevent further infection. This process will take several weeks and will include the inspection of the heating, ventilation, and air conditioning systems ensuring the original equipment manufacturers recommended maintenance schedules are followed and filters are replaced. The company will also contract out a licensed ventilation engineer or scientist to inspect the ductwork for water incursion or microbial growth. 

Several other measures being taken to determine the root cause of the infection include a deep cleaning of the facility, testing of raw materials, and an on-site health hazard evaluation. Identifying the source of the fungal infection may prove difficult since Blastomyces fungi is native to the Midwest and especially common in areas surrounding the Great Lakes. 

Blastomycosis is a serious fungal infection that comes from inhaling spores. They are typically found in moist soil and decomposing matter, such as wood or leaves, and become airborne when disrupted. Mild symptoms include fever, fatigue, and cough. A more severe infection can result in death, create lung complications and spread to the spine or other parts of the nervous system. It can also cause serious symptoms in those with weakened immune systems. The CDC says the infection is non-contagious and can be treated with antifungal medications.

biology of blastomycosis

The first diagnoses at the Michigan paper mill came in early March and to date there have been 21 confirmed and 76 probable cases of blastomycosis. One person has died and 12 of the 97 individuals infected were hospitalized. The mill currently employs over 800 individuals and all infections have been contained to mill employees or visitors. When the mill learned of the first infections, they called on the National Institute for Occupational Safety and Health.

The NIOSH recommended precautions including providing N95 respirators to workers, inspecting the ventilation systems, and limiting projects that have the potential to stir up soil and distribute pores. The agency is expected to return at the end of April to review maintenance protocols and further aid in the investigation by offering urine tests to screen for missed fungal infections, collect samples from the property, and interview workers in an attempt to track down the original source of this fungus.

The current outbreak at the industrial paper mill is the largest reported outbreak of blastomycosis in US history and the mill is taking the necessary precautions to prevent further infection and will place employees on paid leave while the mill is inoperable.

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Natalie Johnson

Natalie Johnson is the previous editor/website administrator for, and is currently a student at Campbell University Norman Adrian Wiggins School of Law.

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Natalie Johnson

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