Health officials in Michigan said 109 cases of the rare fungal infection blastomycosis have been linked to a paper mill in Escanaba, an increase of five cases since the last update a week ago.
Among the 109 cases, 13 have been hospitalized, and one death was previously reported. All the cases are among employees, contractors or visitors to the Billerud Paper Mill, according to Public Health Delta & Menominee Counties. Billerud idled mill operations last month to allow additional cleaning and said in a statement Monday that it’s targeting a May 8 startup date.
Although the number of blastomycosis cases has increased since the previous update, that doesn’t necessarily mean exposures are ongoing, the county health departments said Friday. Since the incubation period for blastomycosis can range from 21 to 90 days, “it is likely all cases had an exposure prior to the mill idling operations,” the agencies said.
“While we continue to see new cases testing positive for blastomycosis and being reported to Public Health Delta & Menominee Counties, we continue to see fewer new cases being reported each week and many of these cases have been showing signs and symptoms since March,” department health officer Michael Snyder said in a statement.
Blastomycosis is caused by a fungus, blastomyces, that lives in the environment, especially in moist soil and decomposing matter like wood or leaves, according to the US Centers for Disease Control and Prevention. It is predominantly found in the Midwest and the South, particularly around the Ohio and Mississippi rivers and the Great Lakes.
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There are only 1 or 2 cases per 100,000 people each year in states where blastomycosis is a reportable condition, according to the CDC. One analysis found 1,216 deaths related to the illness from 1990 to 2010.
People can breathe in these microscopic fungal spores, and although most of them won’t get sick, some will develop symptoms such as fever or cough between three weeks and three months later, the CDC said. Other symptoms can include chest pain, trouble breathing, night sweats, fatigue, weight loss, and muscle or joint pain, according to local health officials. In rare cases, the infection can spread outside the lungs to places such as the skin, bones, brain and spinal cord.
Blastomycosis does not spread from person to person. It’s treated with antifungal medication that must be taken for a period ranging from six months to a year, depending on the severity of the illness and the person’s overall health.
CNN’s Katherine Dillinger contributed to this report.