HERMISTON — The number of coronavirus cases linked to Lamb Weston’s french fry production facility in Hermiston climbed to 142 last week, according to data from the Oregon Health Authority.

It is the third-largest workplace outbreak of the virus in the state to date, but far from the first big outbreak at an Oregon food processor.

Coronavirus outbreaks at food processors and agricultural sites have infected nearly 1,000 workers and close contacts in Oregon since March. Additionally, an outbreak in May at Firestone Pacific Foods, a fruit processor in Vancouver, was linked to 132 coronavirus cases.

Workplace outbreaks helped seed the coronavirus in Oregon during the first few months of the pandemic, but now they’re being outnumbered by what state health authorities term “sporadic spread” — cases with unclear origins.

Of the 60 active workplace outbreaks of five or more cases reported by the Oregon Health Authority in the last week week, 25 are at food processors or agricultural sites.

Three of the five largest workplace outbreaks in the state to date are at food processors.

An outbreak at Pacific Seafood in Newport in June was linked to 181 cases. It’s Oregon’s second-largest outbreak, trailing only the outbreak at the Oregon State Penitentiary. A total of 61 coronavirus cases have been linked to a May outbreak at Bob’s Red Mill in Milwaukie, marking the fifth-largest workplace outbreak in the state.

Fewer large outbreaks have been linked to Oregon farms, but farmworker advocates worry that state regulations won’t prevent major outbreaks at farms as the harvest season ramps up this summer.

The largest Oregon farm outbreak occurred at Townsend Farms in Fairview, where 56 seasonal farmworkers tested positive for the virus in May. The outbreak followed a separate outbreak at the farm in April when 51 people tested positive for the virus.

The outbreak at Lamb Weston quickly grew into one of the largest workplace outbreaks in the state after the company was informed on June 15 that four employees had tested positive for the virus.

Joseph Fiumara, Umatilla County’s public health director, said the county has worked with Lamb Weston to test every employee and do contact tracing since the outbreak at the facility was reported. Fiumara said the county believes it has now connected with everyone who may have been exposed to the virus through the outbreak. The county has 30 contact tracers.

Shelby Stoolman, a spokesperson for Lamb Weston, said 100 employees at the Hermiston facility have tested positive for the virus. Additionally, 42 close contacts have tested positive, based on data provided by the Oregon Health Authority.

Stoolman said the no Lamb Weston employees have been hospitalized as a result of the outbreak. It is not clear whether any of their family members or other close contacts have been hospitalized.

Lamb Weston, one of Umatilla County’s largest employers, closed its Hermiston facility for three weeks following the outbreak. Staff members were paid to stay home during that time. Stoolman said the company reopened the facility in a modified capacity with a limited staff. The company has required employees to wear masks, maintain physical distance and complete health and temperature screenings upon arrival since mid-April, he said, and has made modifications to its break rooms, added new break areas and implemented staggered arrival schedules.

The outbreak at Lamb Weston is one of eight active workplace outbreaks in Umatilla County, according to the Oregon Health Authority. Twenty-one cases have been linked to snack product producer Shearer’s Foods since the end of June, while 17 cases have been linked to staffing and recruiting company Atkinson Staffing since mid-June.

Fiumara said he is concerned that some outbreaks have occurred after employees went to work with minor symptoms and later tested positive for COVID-19.