A much bigger McDonald’s lawsuit is about to “erupt” in the wake of its E. coli outbreak, food safety lawyer says.

McDonald’s just got hit with it the first trial regarding an E. coli outbreak that resulted in Quarter Pounders being pulled at 20% of all McDonald’s locations in the US. But a prominent food safety advocate believes the first trial related to the E. coli outbreak is not one that may have a ripple effect on the food industry.

Greeley, Colo. resident Eric Stelly is suing McDonald’s for liability, negligence and breach of implied warranties, according to a process filed on Wednesday. Stelly claims that two days after buying food from McDonald’s earlier this month, he experienced nausea, cramps and bloody stools that prompted him to seek medical attention. It tested positive for E. coli. According to the complaint, the Weld County Department of Public Health told him his food poisoning was related to McDonald’s food.

“American consumers should have confidence that the food they are serving is free from contamination,” said Stelly’s attorney, Ron Simon. wealth in an emailed statement. “McDonald’s has violated that trust and will now have to earn it back.”

Stelly is one of about 50 patients sickened by E. coli linked to an outbreak of McDonald’s Quarter Pounders. One person has died and 10 have been hospitalized in the outbreak, according to the Centers for Disease Control and Prevention. The Food and Drug Administration has launched a probe in Taylor Farms, one of McDonald’s suppliers, as the source of the outbreak, and Taylor Farms is recalling batches of yellow onions produced at a Colorado plant following the outbreak. Taco Bell, Pizza Hut and KFC they are all pulling the onion from certain locations, but the company did not disclose the source of the ingredient.

The E. coli outbreak represents McDonald’s biggest food safety disaster in more than three decadesaccording to food safety attorney Bill Marler, who plans to represent three clients in lawsuits against McDonald’s over the E. coli outbreak and previously represented Taylor Farms. Following the CDC’s announcement of the outbreak Tuesday night, McDonald’s stock down as much as 9%.

Stelly’s lawsuit against McDonald’s is shocking, Marler said, because it attacks a fast-food giant with a generally solid reputation among food safety experts. But the lawsuit more likely to make waves in the restaurant industry likely won’t come from an individual seeking personal damages, but rather from two food giants going head-to-head.

“The litigation between the victims and McDonald’s and Taylor Farms will pale in comparison to the litigation that will erupt when McDonald’s sues Taylor Farms,” ​​Marler said. wealth. “It’s going to be a big problem.”

McDonald’s and Taylor Farms did not respond wealthhis request for comment.

The grand scheme of things

Taylor Farms, which has approximately 20,000 employeesis “a big player in the grocery industry,” Marler said, because it supplies pre-cut and packaged vegetables to mega-retailers such as Walmartas well as products for restaurant chains like Chipotle. But the company also faced problems with frequent recalls and outbreaks for years, including links to some of the 600 cases of the parasitic intestinal disease cyclosporiasis confirmed in 2013, the largest such outbreak since 1997.

McDonald’s next steps immediately after containing the E. coli outbreak will be to examine and possibly modify its supply chain, Marler said. But then — if Taylor Farms is found responsible for the outbreak — the fast-food giant will likely turn its attention to suing its onion supplier.

“It will be interesting to see what they make of it,” Marler said. “But I have to believe they’ll beat the crap out of Taylor Farms.”

With a growing number of claimants expected to emerge from the E. coli outbreak, only the more serious cases are likely to see significant settlements. In cases of severe E. coli infections, such as hospitalized children with acute kidney failure, McDonald’s could dole $20 million to $30 million to victims, Marler said. But the information now known about the outbreak suggests that McDonald’s took swift action to reduce the spread of E. coli.

“I don’t like to ignore how seriously ill these people are … but in the scheme of 30 years of experience dealing with these cases – where outbreaks are sometimes in the thousands – (it’s) a relatively small outbreak,” said he. .

This story was originally presented on Fortune.com