The Foster Farms chicken processing plant on Cherry Avenue in Fresno, Calif., is one of three plants linked to a salmonella outbreak that has sickened at least 338 people across the country.Craig Kohlruss/The Fresno Bee via Associated Press

Each month, the U.S. Department of Agriculture publishes a list calling out chicken processing plants across the country that have failed salmonella testing. Notably absent from its October report: the three Foster Farms plants in Central California that have been linked to a virulent outbreak.

Those facilities in Fresno and Livingston easily passed, receiving high marks from federal inspectors for controlling the human pathogen on their young chicken carcasses, according to Daniel Engeljohn, assistant administrator with the USDA’s Food Safety and Inspection Service.

But inspectors don’t routinely test the chicken for salmonella once it’s chopped up into parts, like drumsticks, breasts and thighs, to be packaged and sold. And it’s in that secondary processing that food safety regulators speculate the contamination may have spread.

The outbreak has exposed weaknesses in the country’s food safety system, which is designed to spot salmonella at one stop in the journey from the typical bird’s birth to its perch in the supermarket refrigerator case. And, even as the plants continue operating, neither federal regulators nor Foster Farms officials have publicly pinpointed the cause of the outbreak.

There are no federal rules for how much salmonella is acceptable in chicken parts. Federal regulators say they’re developing them. But even if those rules had existed already, it is unlikely they would have caught the problem at the Foster Farms plants.

And if inspectors had raised the alarm before the outbreak of foodborne illness, the best they could have done is pressure the plants to improve their processes. A famous court case involving beef and salmonella found the USDA did not have the authority to close a plant that consistently failed its testing for the human pathogen.

Meanwhile, the rate of salmonella infection in the United States is holding steady with no sign of going down, while Europe has managed to cut its rate dramatically in a five-year period, according to the European Food Safety Authority. That’s in part because some European countries test for salmonella at the beginning of the process – when the chickens are being raised for slaughter.

In the current outbreak traced to the California Foster Farms plants, 338 people had been reported infected with seven strains of salmonella Heidelberg as of Oct. 17. Those strains are antibiotic-resistant, which might be contributing to the high rate of hospitalization associated with the outbreak. It has sickened people in 20 states and Puerto Rico, though most of the cases have occurred in California. For every reported illness from salmonella, the Centers for Disease Control and Prevention estimates 29 more cases might remain unreported, putting the likely toll closer to 10,000 infections.

Since January, federal inspectors have documented food safety violations at the three Foster Farms plants, including fecal material on carcasses. But federal food safety officials say those violations are no worse than what you’d see in a typical chicken processing plant.

And those same plants had such a strong record on salmonella that their young chicken carcasses were tested for it by federal inspectors only about once every two years, Engeljohn said.

In the most recent tests, which took place within the year, fewer than 2 percent of the carcasses tested were tainted with the human pathogen. Under federal rules, no more than 7.5 percent of broilers tested should show evidence of the bacteria, which underscores that some salmonella is tolerated in chicken meat in the United States.

At these three Foster Farms facilities, something appears to have gone wrong later in the process. Exactly what happened is still unclear. If the company knows what happened, it has not disclosed it.

A truck enters the Foster Farms chicken processing plant in Livingston, Calif. Food safety regulators speculate that salmonella contamination at the plant may have spread during secondary processing, when whole birds are chopped into parts, like drumsticks, breasts and thighs, to be packaged and sold.
Rich Pedroncelli/Associated Press

The federal government does not typically inspect chicken for salmonella once it’s been chopped into parts from whole. It did so at these three plants once the outbreak happened, though the rates it discovered were only slightly higher than those found at other plants across the country.

The government estimates 24 percent of all chicken parts have salmonella at plants nationwide. The Foster Farms plants had between 25 and 27 percent.

In response to the outbreak in early October, the USDA’s Food Safety and Inspection Service threatened to shut down the plants by withdrawing its inspectors, who have to be on-site for the plants to operate. Under pressure, the company said it would implement new processes. The plants stayed open.

One change at the plants: Chicken parts now will be washed with an antimicrobial treatment, according to the USDA. This is done already at another Foster Farms plant in Washington state, where federal inspectors found a much lower rate of salmonella on chicken parts.

“They’re treating their parts with an additional antimicrobial treatment, which all of the rest of the industry does not use, which we’re encouraging the industry to do,” Engeljohn said. Regulators do not have the authority to mandate that all plants adopt that treatment.

Yet, even if the federal government develops performance standards for salmonella on chicken parts, the USDA is unlikely to shut down facilities that do not meet those standards before people get sick. A pivotal 2001 court case, Supreme Beef Processors v. USDA, found that the agency cannot close a meat processing plant that consistently fails salmonella testing because, in this country, the bacteria is not considered an “adulterant” in meat.

That means it’s treated as an unfortunate food safety hazard and a natural constituent of poultry that consumers should cook properly to destroy. Once something is considered an adulterant, like E. coli O157:H7 in ground beef, it cannot legally be sold as food for humans unless it has been inactivated by cooking or some other process.

When a poultry plant fails its salmonella testing, federal inspectors put pressure on the company to improve its processes. Plants that have failed also are tested more often to ensure they’re cleaning up. If a facility repeatedly fails these tests, the agency can threaten to withdraw its inspectors to shut it down. But it is unlikely that the USDA will actually do so, or else risk being sued as it was in the Supreme Beef case. 

This story was edited by Andrew Donohue and copy edited by Nikki Frick and Christine Lee. 

Katharine Mieszkowski

Katharine Mieszkowski is a senior reporter and producer for Reveal. She's also been a senior writer for Salon and Fast Company. Her work has appeared in The New York Times, Rolling Stone, Mother Jones, Slate and on NPR's "All Things Considered."

Her coverage has won national awards, including the Alfred I. duPont-Columbia University Award two years in a row, an Online News Association Award, a Webby Award and a Society of Environmental Journalists Award. Mieszkowski has a bachelor's degree from Yale University. She is based in Reveal's Emeryville, California, office.