Reported cases of the novel coronavirus linked to an outbreak at a sleep-away camp in Hope Township, Mich., are on the rise.

On Tuesday, cases increased to 35, up from 21 on Monday. There are also seven probable cases as of Tuesday, Sarah Surna of the Barry-Eaton District Department of Health, told Fox News.

The Barry-Eaton District Health Department said the cases are related to an outbreak of the virus at an outdoor campground at Camp Michawana which is located just outside of Hastings.

The outbreak was first reported Aug. 6 when five staff members and one camper tested positive for the virus, according to the Barry–Eaton District Health Department website.

“We estimate that approximately 250 persons attended or staffed the camp in the past two weeks and are at greatest risk of exposure. Approximately 180 campers were children under 18 who attended the children’s overnight camp either last week or this week. An additional 70 persons were either attendees at the family-style camp or staff of the camp," the Barry-Eaton District Health Department said in a press release on Thursday.

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The local health department stated in the release it was working with the camp management to notify people who had been directly exposed and noted that many live outside the area. Officials said anyone who attended or stayed at Camp Michawana -- which contains a family camp, children’s overnight camp, and a campground -- on or after July 24th may have been exposed.

A group of campers may have been exposed to coronavirus in Michigan Camp (Credit:Halfpoint / iStock)

"The way Camp Michawana operates, it's very challenging for us to tell who is exposed and who was not exposed because there's so much movement. Because of this challenge, we acted out of caution and considered everyone exposed,” Sarah Surna, Barry-Eaton County Health Department Community health promotions specialist, told news outlet WWMT-TV3

Surna told the news outlet health officials were performing contact tracing and case investigation. "Some of the best tools we have to prevent the spread of the disease is contact tracing and case investigation," she said in the interview.

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Gov. Gretchen Whitmer on Thursday signed an executive order requiring face masks to be worn by children attending daycare and camps. The new measure requires that staff and children ages 12 and older must wear a mask in cabins or similar indoor settings and classrooms. All staff and children 2 years old and older must wear face coverings on school buses, while those 4 years old and older are required to wear them in hallways and common areas.

Previously, camps and child care centers were not mandated to wear masks inside enclosed public spaces and crowded outdoor places.

"While I can't say if Camp Michawana outbreak would have been prevented, we encourage wide use of masks at Barry-Eaton County Health Department because we know masks work," Surna said to the TV outlet.

The Barry-Eaton District Health Department recommends that these individuals self-quarantine at home for 14 days past the last date of their stay at the camp and monitor themselves for signs of COVID-19. Anyone who experiences symptoms is encouraged to get tested immediately.

The camp is now closed to visitors for two weeks.

As of Monday, Barry County had a total of 164 cases of COVID-19, according to the Barry-Eaton county website.