A team from the Centers for Disease Control and Prevention has arrived in Sioux Falls, South Dakota, to help with the Smithfield Foods coronavirus hot spot, which has become the biggest single source of cases in the United States.

Eighty of South Dakota's 180 new COVID-19 cases are employees of the meat-processing company, bringing the total to 518 Smithfield Foods employees who have tested positive. There are also now 126 total cases of non-employees that became infected when they came into contact with a Smithfield employee, according to the South Dakota Department of Health.

The 518 employees and 126 non-employees connected to Smithfield makes it the largest cluster in the country (644), according to tracking by The New York Times. The previous top cluster was 585 cases aboard the USS Theodore Roosevelt in Guam.

Fact check:Smithfield Foods is not selling meat that was slaughtered, processed in China

Smithfield announced Sunday that it would be closing its Sioux Falls plant indefinitely Wednesday. The plant has 3,700 employees.

Gov. Kristi Noem said the state is "aggressively testing" Smithfield employees and people who have come into contact with them, as well as getting people into isolation as soon as possible.

The CDC team is scheduled to tour the Smithfield plant on Thursday morning and create a checklist of items to complete before the plant can reopen, Noem said during a press conference on Wednesday. Noem said she's working with federal officials and Smithfield leaders to get the plant back online to provide relief for pork producers and the food chain.

Health Secretary Kim Malsam-Rysdon said they requested the CDC bring in occupational health experts to help the state understand Smithfield's coronavirus situation and what the company can do to protect its workers. Smithfield is cooperating with the state, and they look forward to the mitigation efforts so the plant can reopen, Malsam-Rysdon said.

United States hot spots

Smithfield Foods meatpacking plant; Sioux Falls, S.D. 644

Aboard the U.S.S. Theodore Roosevelt; Guam, 585

Cook County Jail; Chicago, 524

Parnall Correctional Facility; Jackson, Mich., 212

Soldiers' Home in Holyoke; Holyoke, Mass., 194

Source: The New York Times