Iowa had its largest single-day increase in COVID-19 cases Sunday, driven largely by new positive tests at meatpacking plants.

State officials said 261 of the 389 new cases of COVID-19 reported Sunday were discovered as part of testing done at Iowa meat processing plants.

The spike comes one day after Iowa recorded its most COVID-19-related deaths in a single day. Ten additional deaths of Iowans were reported Saturday, according to the Iowa Department of Public Health. The state recorded one additional death on Sunday.

Officials tested more than 1,000 meatpacking employees at Tyson Foods and National Beef Packing Co. — 84 Tyson employees and 177 National Beef workers tested positive for the virus.

Tyson Foods has several packing plants in Iowa and National Beef operates a facility in Tama County.

“We knew it was coming. It’s kind of been boiling up all week,” said Rep. Timi Brown-Powers, D-Waterloo, where Tyson Foods operates a pork processing plant that has seen a spike in COVID-19 case.

Local officials in Waterloo have called on Tyson to close the plant as coronavirus continues to spread in Black Hawk County.

“My personal opinion is that it should be closed,” Black Hawk County Sheriff Tony Thompson told the Register last week. "I think we need to deep-clean that facility and I think we need to restart that plant on a clean slate.”

As of Sunday, 192 people in Black Hawk County had tested positive and one person had died.

► MORE: The latest on the coronavirus outbreak in Iowa

Tyson Foods halted production at its Columbus Junction pork plant on April 6 after more than two dozen workers tested positive and two employees died from COVID-19 complications.

The company announced Sunday that it would close its Perry plant on Monday for one day of "additional deep clean."

"Our plant production areas are sanitized daily to ensure food safety, and we have significantly stepped up deep cleaning and sanitizing of our facilities, especially in employee breakrooms, locker rooms and other areas to protect our team members," Tyson spokeswoman Liz Croston said in an email.

National Beef announced last week that its Iowa Premium plant in Tama would close until April 20 after numerous employees tested positive.

The 389 new cases the state reported Sunday — which make up 13% of the confirmed positive cases in Iowa — are more than double the previous one-day record increase of 191 on Friday.

The single death reported Sunday was an older adult (age 61-80) in Muscatine County. There are 198 Iowans currently hospitalized due to coronavirus and 1,171 have recovered from the virus, state data shows.

Complaint filed over worker protections

Linn County had the largest increase in new positive tests Sunday with 63 new cases. Three of the new cases were tied to Heritage Specialty Care, a long-term care center that has been one of the hot spots for COVID-19 in Iowa.

Gov. Kim Reynolds on Thursday ordered people in northeastern Iowa, where Linn County is located, to limit their activity, including keeping visits to only immediate family members.

Several counties with meatpacking plants, including Black Hawk, Louisa and Marshall counties, reported more than 20 positive cases.

The largest increases were in:

Linn, 63

Marshall, 42

Polk, 40

Scott, 36

Washington, 35

Louisa, 35

Muscatine, 31

Tama, 28

Black Hawk, 26

Johnson, 20

The concentration of cases has highlighted the particular susceptibility of meat processing workers, who stand shoulder-to-shoulder on the line and congregate in crowded locker rooms and cafeterias. As many as half a dozen plants nationwide have shut because of outbreaks.

The Smithfield Foods plant in Sioux Falls, South Dakota, shut down last week. It has reported 518 infections in employees and another 126 in people connected to them as of Wednesday, making it among the largest known clusters in the United States.

The companies running the meatpacking plants, like Tyson and JBS USA, which operates a plant in Marshalltown, have started taking employees' temperatures before shifts, providing protective equipment and suspending attendance policies.

“The worst is yet to come,” said Joe Henry, political director for the League of United Latin American Citizens of Iowa.

Democratic lawmakers representing Waterloo on Sunday filed a complaint to the Iowa Division of Labor, saying Tyson was not adequately protecting its employees from the virus.

“What we are seeing play out is borderline criminal,” Sen. Bill Dotzler, D-Waterloo, said in a news release. “I represent workers who are telling me that even the voluntary precautions being taken aren’t doing anything. They’re having temperatures taken and the results ignored. These workers then go to work in close proximity throughout their shifts, go out into the community and expose community members, then go back into the plant where it all starts over again.”

Croston, the company spokeswoman, said Tyson has been working to mitigate the spread of COVID-19 since January.

The company takes employees' temperatures before work and all employees wear face coverings, she said. Sick workers are told to stay home and dividers have been installed between workstations.

'You can see it in their eyes; they’re scared'

Brown-Powers, who worked a coronavirus testing site Sunday afternoon in Black Hawk County, said she can sense the fear among Tyson employees.

She said 75% of the people seeking COVID-19 tests in Black Hawk County are linked to the plant, which employs 2,700 workers.

“You can see it in their eyes; they’re scared,” she said.

Marshall County, where 42 new positive cases were reported Sunday, is home to a JBS meatpacking plant.

In an interview Sunday, Henry said Iowa's 18 meatpacking plants are becoming "incubators" for COVID-19. With 70% of the nation's pork production plants within 250 miles of Des Moines, outbreaks could threaten the state, he said.

LULAC plans to boycott some of the largest meat producers beginning this week.

On Sunday afternoon, JBS and United Food and Commercial Workers International Union announced an agreement to raise pay by $4 per hour for its workers, including 2,000 workers in Marshalltown.

The temporary pay increase will run through May 30. UFCW said in a news release that JBS employees would also get access to more personal protection equipment and Plexiglas shields would be installed in between workers where social distancing isn't possible.

“We hope JBS’s leadership sends a message to all other companies — union and non-union," UFCW International President Marc Perrone said in a statement. "Now, more than ever, it is critical that not only is our food supply protected, but that food processing and meatpacking workers are protected as they perform such an essential role during this health crisis.”

Associated Press contributed to this report.

Austin Cannon covers the city of Des Moines for the Register. Reach him at awcannon@registermedia.com or 515-284-8398. Your subscription makes work like this possible. Subscribe today at DesMoinesRegister.com/Deal.