The wave of meat-plant closings because of coronavirus keeps rising as a second Minnesota processor — Comfrey Farm Prime Pork — has been idled along with a giant Tyson Foods pig slaughterhouse in Iowa.

COVID-19 cases also have surfaced at meat plants in Minnesota owned by Hormel Foods, though none have prompted closures. Many U.S. meatpacking plants, where hundreds of people work in proximity, have become hives for the virus.

Comfrey Farm Prime Pork in Windom said in a statement late Tuesday that it would be closed until Friday while it does a "deep clean sanitization" and establishes more preventive measures against the virus.

"When we discovered our first positive case of COVID-19 at the plant, we immediately activated Comfrey Farm Prime Pork's COVID-19 response plan," Tom Seigfreid, the company's chief financial officer, said in a statement.

The company said two of its 660 workers tested positive for COVID-19, and that it suspended production "given the rapid progression of COVID-19 in the area."

Windom is about 30 miles from Worthington, site of a big JBS USA pork plant that was shuttered indefinitely Monday due to a significant coronavirus outbreak.

Comfrey Farm Prime Pork processes 5,200 hogs a day, 26% of the JBS plant's volume. It is owned by Glen Taylor, who also owns the Star Tribune.

Tyson Foods, one of the nation's largest pork packers, suspended operations Wednesday at its Waterloo, Iowa, plant. The Arkansas-based company had kept the plant open in recent days over the objections of alarmed local officials.

More than 180 infections have been linked to the Waterloo plant and officials expect that number to dramatically rise.

The Tyson plant can slaughter 19,500 hogs per day, accounting for 3.9% of U.S. pork-processing capacity. It is one of the Midwest's giant pig-slaughtering plants, along with JBS USA's Worthington plant and Smithfield Foods' operation in Sioux Falls, S.D., which also is idled.

More than 500 workers at the Sioux Falls plant, which accounts for 4% to 5% of the nation's pork, have been infected with COVID-19, one of the country's largest localized outbreaks.

JBS' Worthington plant, which employs more than 2,000, also processes about 4% of the nation's pork supply. That plant is at the center of perhaps the worst outbreak in rural Minnesota.

Just a week ago, there were only two COVID-19 cases in Nobles County, where the JBS plant is located, according to the Minnesota Health Department. Now there are 126 cases, including one death.

At Minnesota's largest pork complex in Austin, there has been one COVID-19 case at the Hormel Foods plant and none at Quality Pork Processors facility directly next door, said Richard Morgan, president of United Food and Commercial Workers Local 9, which represents workers at both plants.

Hormel confirmed that one employee tested positive in early April "and should be back to work soon."

Hormel's Austin plant employs 1,580 union workers who turn slabs of pork into everything from bacon to ham and Spam. Quality Pork, a separate company that employs around 1,100, slaughters hogs that supply the Hormel plant.

Both companies have supplied cloth masks to workers, Morgan said. "Where it was possible, they have social distanced and where it wasn't, they have put up plastic barriers [between workers]."

Hormel also confirmed that employees had tested positive for COVID-19 at its Jennie-O Turkey Store processing plants in Willmar and Melrose, though the company declined to say how many.

Jennie Lippert, Kandiyohi County's health and human services director, said two Jennie-O employees in Willmar tested positive. "Based on the size of the employer, I assume there are going to be more," she said.

Jennie-O, which also has corporate offices in Willmar, is Kandiyohi County's largest employer with 1,650 workers, according to a county website. Jennie-O is one of the nation's largest turkey processors and also has plants in Faribault and Barron, Wis.

No Jennie-O plants have closed. Two food factories owned by Hormel and another half-owned by the company — all three outside of Minnesota — have been temporarily closed due to COVID-19 concerns, including after some workers tested positive.

"The vast majority of our [more than 30] production facilities continue to operate with minimal disruption to our supply chain," Hormel said in a statement. "We continue to have the highest sanitation and food safety standards in all our production facilities."

The Associated Press contributed to this report.

Mike Hughlett • 612-673-7003