Wisconsin sees its largest single-day increase in coronavirus cases and its first children with multisystem inflammatory syndrome

The state Department of Health Services reported 733 new cases of coronavirus Friday, Wisconsin's largest single-day increase — by more than 100 cases — since the pandemic began.  

Friday's new cases accounted for about 5.4% of the more than 13,600 tests processed since Thursday.

That's also a new record for the number of tests run in a single day, up significantly from Thursday's record-setting number of 10,626. 

As of Friday afternoon, 17,707 Wisconsinites had tested positive for the virus and 568 had died, an increase of 18 from the previous day. About 60% had recovered, and more than 233,500 people had tested negative.

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There were 423 people hospitalized with COVID-19 across the state Friday, about a third of them in intensive care, according to the Wisconsin Hospital Association. Among inpatients, 243 had pending coronavirus tests as of Friday.  

Hospitalizations due to COVID-19 are generally slightly up compared to early May, when they briefly dipped below 300.

New COVID-related illness found in Wisconsin children

Among those who have been hospitalized: seven children believed to be suffering from multisystem inflammatory syndrome, the first known cases in the state, officials at Children’s Hospital of Wisconsin said Friday. 

The new illness affects children who have been infected with or exposed to the coronavirus. It causes swelling in organs such as the heart, lungs, kidneys, brain, stomach and intestines. It also can cause a persistent high fever, abdominal pain, vomiting, diarrhea, rash, swelling of the hands and feet, and red eyes and tongue.

So far, most children diagnosed with the syndrome nationwide "have gotten better with medical care," according to the national Centers for Disease Control and Prevention.

All of the patients with suspected cases identified at Children’s are younger than 5, according to a hospital spokesman. As of Friday, two remained hospitalized in good condition, while the other five were discharged after brief hospital stays and doing well at home.

Frank Zhu, medical director for infection control and prevention control at Children's, is part of the team investigating the syndrome.

"We do not know for sure, but the current working diagnosis is this is likely a post-infectious complication of COVID-19," he said. "These patients obviously often do not have positive tests in their nose for the virus, but have positive antibodies ... which suggests to us that this is likely not infectious."

The cases have been referred to the Wisconsin Department of Health Services.

Waupun prison has more than 200 cases

Another significant group among Friday’s numbers came from Waupun Correctional Institution, where 213 inmates have tested positive out of about 600 results received so far — a positive rate of about 35%, according to department spokeswoman Anna Neal. Fifteen Waupun staff members also had tested positive as of Friday.

Neal would not say whether any inmates had been hospitalized with COVID-19.

At Waupun, 184 of the positive results came after three days of testing by the Wisconsin National Guard, Neal said. The other 29 inmates with positive results had been tested earlier.

The numbers on the department's website will be updated once all the results from the National Guard's testing are available, she said. As of Friday afternoon, the site said 213 of 231 tests at Waupun had come back positive.

The corrections department is in the process of testing all inmates and staff members throughout the state. Waupun has by far the highest number of infections among Wisconsin's prisons.

Statewide, 7,050 inmates have been tested by the National Guard. In addition to the 184 Waupun inmates, 33 inmates around the state have tested positive. Mass testing has also been completed at Marshall E. Sherrer Correctional Center, Felmers O. Chaney Correctional Center, the Milwaukee Women's Correctional Center and the Milwaukee Secure Detention Facility, according to Neal.

Air show canceled, restaurants closed

The pandemic has continued to wreak havoc on summer activities and local businesses as well.

In a statement released Friday, organizers announced cancellation of the Milwaukee’s annual Air & Water Show, which would have included a headlining appearance by the U.S. Navy Blue Angels Flight Demonstration Team.

“The rare and exceptional opportunity to host the Navy Blue Angels made this a very tough but necessary decision to make,” Milwaukee Air & Water Show President Paul Rogers said in a statement.

In Waukesha, two restaurants that reopened quickly closed again after employees tested positive for coronavirus.

One of them, Sobelmans Pub & Grill, closed less than a day after announcing on social media it had reopened.  

The restaurant, located on Williams Street at the edge of Waukesha's downtown commercial district, wasn't ordered to close by the health department, but its owners felt it was best to be cautious, according to the Sobelmans Facebook page.

"Our remaining staff, who have been wearing face masks as a precaution, have been referred to the (Waukesha County) Health Department and we will not reopen until everyone is cleared — the health of our staff, customers and community is paramount," the posting says.

The Waukesha location of Casa Tequila also has closed temporarily after a brief reopening. There, a cook was diagnosed with COVID-19.

Only the Waukesha location, at 2423 Kossow Road, is closed, according to the restaurant's Facebook page. The other Casa Tequila restaurants, in Pewaukee, Hartford and West Bend, remain open.

Carol Deptolla, Jim Higgins, Mark Johnson and Ricardo Torres of the Journal Sentinel staff; and Madeline Heim and Jim Riccioli of the USA TODAY NETWORK-Wisconsin contributed to this report.

Contact Gina Barton at (414) 224-2125 or gbarton@gannett.com. Follow her on Twitter at @writerbarton.