GRAND RAPIDS, Mich. (WOOD) — After sitting idle for 25 days and undergoing a deep cleaning, the Billerud paper mill in Escanaba is back up and running.

The company announced that operations resumed Monday after shutting down on April 13 due to a Blastomycosis outbreak that caused more than 100 employees, contractors and visitors to fall ill.

“(Following the cleaning), no blastomyces spores have been found within the mill. The health and safety of our employees and contractors remains our top priority and we are focused on ensuring a safe return to the mill,” the company said in a statement. “We continue to work closely with and follow the recommendations of local, state and federal health experts as they continue to investigate this dynamic situation.”

Billerud says the company was first notified about possible blastomycosis infections on March 3. The local health department for Delta and Menominee Counties (PHDM) was notified by a local hospital that they had seen a spike in atypical pneumonia infections, all from people affiliated with the mill.

Follow-up testing, which can take a couple of weeks, confirmed that some of the infections were caused by blastomycosis, a type of fungus that grows in moist soil and decomposing matter. Infections stem from directly breathing in the fungal spores, meaning it cannot spread from person to person.

Between March 9 and April 4, the outbreak ballooned from 15 to 81 suspected infections. As of May 5, PHDM has confirmed 115 total cases of blastomycosis, all connected to the mill. Of those 115 cases, 14 people were hospitalized. PHDM reported on April 14 that one patient had died from their infection.

Although the number of cases continues to rise, PHDM warns that exposures are likely over.

“Due to the lengthy incubation time (time from exposure to the fungus to the time one starts to show symptoms) for blastomycosis, it is likely all cases had an exposure prior to the mill idling operations. This incubation periods can range from 21 to 90 days,” the agency stated.

A blastomycosis infection often comes with many symptoms, including fever, chest pain, fatigue, muscle and joint pain, night sweats, difficulty breathing and a severe cough that may occasionally produce blood.

Not everyone who breathes in the spores will develop an infection, but those that do are typically treated with an antifungal medication.

Michigan’s Upper Peninsula is a known risk area for blastomycosis infection. However, PHDM says there has never been an industrial outbreak like this documented in the U.S.

The fungal spores are launched into the air when they are disturbed. PHDM recommends wearing an N95 mask when working in or around moist or disturbed soil or in heavily wooded areas. It also recommends waiting to move leaf litter until it is dry and avoiding digging and disturbing soil on windy days.