Inside America’s largest mold outbreak ever, which sickened hundreds of people and killed one
Health officials are warning of a little-known deadly fungus that caused the largest mold outbreak in U.S. history.
Last February, 162 employees at Billerud Paper in Michigan became ill with blastomycosis, an infection contracted by inhaling spores of the fungus Blastomyces.
Of those, 18 workers were hospitalized with scarring on their lungs that made it difficult to breathe. One patient died.
The outbreak made headlines at the time, but the CDC released its full report this week.
All patients worked or visited the factory and most reported apparently benign symptoms such as coughing and fatigue.
Blastomyces is believed to be found in moist soil, especially in woodland or near water, and in rotting wood.
Researchers warned that despite the paper mill’s location “in a wooded area consistent with Blastomyces habitat,” they could not find the source of the outbreak.
And officials fear the disease is more widespread than previously thought, as most states are not required to report cases.
A Billerud paper mill in Escabana, Michigan (pictured) has reopened after three weeks of closure because it was in the middle of a deadly blastomycosis outbreak
Ian Pritchard, a 29-year-old chef in Michigan, died last year of blastomycosis after the disease made his lungs resemble “Swiss cheese.” It is unclear whether he had any connection with the paper mill in Billerud
Blastomycosis kills one in five patients because spores destroy the lungs by causing harmful inflammation, leading to severe pneumonia.
The disease is rare, affecting only two in 100,000 Americans each year. Delta County, where the plant is located, reported only one case per year before the outbreak.
CDC officials wrote in the report, “This outbreak was the largest documented outbreak of blastomycosis in the United States, and the first linked to a paper mill or industrial setting.
‘A coordinated public health response enabled rapid preventative measures with recommendations aimed at reducing worker exposure to Blastomyces, including hazard communication, respiratory protection, factory cleaning and ventilation system improvements.’
In April 2023, the factory voluntarily stopped production for three weeks to upgrade air filters and clean ventilation ducts.
Health authorities held information sessions for workers on blastomycosis and trained them on protective measures, such as wearing masks.
The report comes nearly a year after 29-year-old Ian Pritchard, a chef from Michigan, died from the disease after it ravaged his body for months.
Mr Pritchard’s father said the disease affected his son’s lung tissue, making it resemble ‘Swiss cheese’.
It is unclear whether Mr Pritchard had any connection to the paper mill.
He lived in Petoskey, about 200 miles from Escanaba, where the plant is located.
According to the CDC report, local health authorities in Michigan were notified in February 2023 of a “cluster of cases of atypical pneumonia” among workers at the plant.
Urine tests were positive for Blastomyces.
“All cases occurred among individuals who worked at or attended the paper mill before the onset of the illness,” CDC experts wrote.
Officials from the National Institute for Occupational Safety and Health (NIOSH) opened an investigation in March 2023 and interviewed 645 of the plant’s 1,000 employees.
More than eight in ten employees were men and 94 percent were white. The average age was 46 years, with the youngest employee being 19 and the oldest being 73.
Most patients experienced coughing (90 percent), shortness of breath (76 percent), fatigue (76 percent) and fever or chills (73 percent).
Just under two-thirds had “abnormal pulmonary findings on chest imaging,” which may include fluid around the lungs or white spots, indicating an infection.
The map above shows states where cases of blastomycosis are confirmed (red), recently confirmed (orange), or suspected (blue)
Mr Pritchard was one of about half of the people exposed to Blastomyces who become ill. The infection is fatal in up to 22 percent of cases
Health authorities were unable to find the source of the fungus, which is usually found in soil and rotting wood in forests and along waterways.
No new cases have been reported since April 2024. Officials estimated that blastomycosis affected one in five factory workers.
The most common symptoms of blastomycosis are fever, cough, shortness of breath, night sweats, muscle pain, weight loss and fatigue.
Some patients also develop skin lesions such as blisters or ulcers.
Bactomycosis is treated with antifungal medications for six months to a year.