GREEN BAY - Brown County now has over 500 confirmed cases of the coronavirus, continuing the rapid spread that began to show up in numbers last week.

It trails only Milwaukee County in the number of cases statewide. Over half the cases, 267, stem from three meat-processing businesses in the county.

A county public health spokeswoman said Wednesday she expects to see numbers continue to rise, and that the health department is so concerned about the growing numbers that it has contacted local police about finding ways to more effectively persuade residents to follow social-distancing rules.

The county reported 511 cases on Thursday, plus six in the Oneida Nation. Twenty-two people are hospitalized, officials said. That compares with 410 cases reported Wednesday in Brown County, as well as the six among Oneida members.

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Statewide, the number of cases stood at 5,052, an increase of 207 from Wednesday, according to the state Department of Health Services. At least 257 people have died.

Brown County cases began to spike around Easter, said Claire Paprocki, speaking for the county Public Health Department. Health officials have so far not seen an increase they would attribute to crowds and long lines at polling places in Green Bay during the April 7 election, but continue to investigate.

The spike that began near Easter prompted the county to request help from the U.S. Centers for Disease Control and Prevention. CDC said Thursday it has sent a four-person team of a veterinarian, data epidemiologist, laboratorian with epidemiological experience and a behavioral scientist.

The team has completed facility tours at two locations and will visit a third in the coming days, said Marcus Hubbard, a CDC spokesman. He did not identify the facilities.

Brown County's new numbers came one day after authorities revealed that 205 cases in the county were linked to three meat-processing operations, including 147 cases tied to the JBS Packerland plant on Lime Kiln Road in Green Bay. On Wednesday, 39 cases had been linked to American Foods Group in Green Bay and 19 to Salm Partners, a Denmark sausage-maker.

On Thursday, the numbers had grown to 189 from JBS Packerland, 55 from American Foods and 23 from Salm.

The case numbers include meatpacking employees and their family members.

The county's health officer has the power to close a meatpacking plant if she deems it a threat to public health or safety, but closures are not being discussed at the moment, Paprocki said. County health officials toured the JBS and American Foods plants this week and found the companies taking steps to prevent spread of the virus inside the facilities, she said.

"They are staggering breaks" to avoid crowds in breakrooms and other small spaces, she said. "They have put plexiglass up" to serve as barriers between employee work stations.

In a news conference Thursday, national representatives of the United Food and Commercial Workers International Union, which represents JBS workers in Green Bay, said they aren't encouraging plant closures unless absolutely necessary. The union is instead pushing for worker access to personal protective equipment, testing and other measures.

“There’s stuff that the government can do to ensure that these workers are safe, and they need to do it yesterday," said Mark Lauritsen, UFCW's international vice president for meatpacking. "That's what we're really advocating for. This union is not going to advocate for all these plants to close down unless it's one of those things that absolutely needs to take place."

For the second straight day, Brown County officials issued a stern warning that residents need to be more serious about avoiding other people. Paprocki said a bonfire with next-door neighbors — even with a commitment to stay 6 feet apart — or a quick visit to church might seem innocuous but increases the chance the virus will continue to spread.

"If you are not in the same unit or same family, do not gather," Paprocki said. Avoiding contact with non-family-members, she said, "is clearly the way" people in Brown can slow the spread.

When people "don't practice social distancing," she said, "this is why we see a spike."

Haley BeMiller of the Green Bay Press-Gazette contributed to this report.

Contact Doug Schneider at (920) 431-8333, or DSchneid@gannett.com. Follow him on Twitter at @PGDougSchneider