A Pennsylvania food manufacturer is recalling 8,757 pounds of ready-to-eat salad products following an E. coli outbreak that has spread to several states and sickened dozens of people.

Fresh Foods Manufacturing, based in Freedom, Pa., is recalling the prepackaged products after learning last week from their romaine lettuce supplier that the vegetables may have been contaminated with Escherichia coli, the U.S. Department of Agriculture said Saturday. Officials said the recalled products have not been tied to any E. coli-related illnesses.

The recalled items, which were labeled “Great to Go by Market District,” were shipped to retailers in Indiana, Ohio, Pennsylvania and West Virginia and had sell-by dates of April 13 to April 16.

The Food and Drug Administration said Friday that the outbreak, which began in mid-March, may have been caused by bagged and pre-chopped romaine lettuce grown in the Yuma, Ariz., region, near the border to Southern California, and distributed to retailers across the country. The agency has not identified specific farms or companies that grew, supplied and distributed the contaminated vegetables.

Thirty-five people from 11 states have become sick; 22, including three people suffering from kidney failure, have been hospitalized, according to the Centers for Disease Control and Prevention. No one has died.

Health officials said these people became ill between March 22 and March 31. The majority of them reported that they ate romaine lettuce within a week before they became sick. Many said they ate salads with romaine lettuce at restaurants, and these businesses told health officials that they used store-bought chopped romaine lettuce.

The highest number of illness was reported in Idaho and Pennsylvania, with eight and nine cases, respectively. Seven were reported ill in New Jersey. The others were in Washington state, Missouri, Illinois, Michigan, Ohio, New York, Virginia and Connecticut. Health officials in Montana and Arizona also said they each have three confirmed cases of E. coli infections. But the CDC, as of its latest announcement Friday, has not linked those cases to romaine lettuce from Arizona, a spokeswoman said.

Bill Marler, a Seattle-based personal injury attorney who focuses on food-borne illness litigation, said the reported illnesses are probably just the tip of the iceberg, partly because it remains unclear how romaine lettuce harvested from the Yuma region made it to retailers and restaurants.

“This stuff went everywhere. It's conceivable that we may be seeing the beginnings of a fairly significant outbreak,” Marler told The Washington Post. “They've linked it to Yuma because that's where romaine this time of year is grown. It's unclear how it made it from Yuma. ... What we don't know is the sort of supply chain in between.”

Romaine lettuce is sometimes packed in the fields and shipped directly to restaurants or grocery stores. But other times, Marler said, the vegetables are taken to a central processing plant, where they're packed under different brands before they're sent to retailers. The latter situation could make identifying the specific origin of contaminated vegetables more difficult, Marler said.

“I think they're going to figure this out, but it may take awhile,” he said. “And we may see these numbers stack up, unfortunately.”

Marler said he's representing eight people from several states who have become ill. Two clients, he said, suffered kidney failures, which generally happen in a small number of cases. One woman had to undergo a blood transfusion. One man's kidneys are not functioning at all, and he is undergoing a treatment called plasmapheresis, a procedure in which blood is separated into cells and plasma.

Health and food safety officials are advising consumers who have store-bought chopped romaine lettuce, including prepackaged salad mixes, to throw the vegetables away even if they’ve been partially eaten. Officials urge restaurants and retailers to not serve or sell romaine lettuce grown in Yuma, and some have warned customers of possibly contaminated vegetables.

Walmart, for example, has sent emails to customers who may have bought recalled items from its stores. Del Taco said it has removed all salad blends from its locations.

The outbreak has been tied to only bagged and chopped romaine lettuce grown from the Yuma region. Romaine grown elsewhere and other forms of romaine, such as whole heads or hearts, are not believed to have been contaminated, according to a joint statement from industry leaders.

“Nearly all of the romaine lettuce now being harvested and shipped throughout the United States is from California growing areas, and is not implicated in the outbreak,” the statement said. “The leafy greens community takes the responsibility for producing fresh produce very seriously.”

E. coli are a type of bacteria found in undercooked beef, raw milk, soft cheeses made from raw milk, raw fruits and vegetables, and contaminated water. Most E. coli bacteria are not harmful, but one type known as E. coli O157: H7 produces a toxin called Shiga, which destroys red blood cells, causes kidney failure and bloody diarrhea. Other kinds of E. coli cause urinary tract infections, respiratory illness and pneumonia.

“Individuals with this infection usually get better within about five to seven days; however, some illnesses can be serious or even life-threatening,” said Shereef Elnahal, commissioner of the health department in New Jersey, which first reported a high number of cases.

Health officials said children under the age of 5, seniors older than 65 and those with weak immune systems are most vulnerable. So far, the outbreak has sickened people ages 12 to 84.

Last year, products of the Illinois-based SoyNut Butter were recalled because of possible E. coli contamination. Thirty-two people from a dozen states were sickened, the CDC said. The company, which produced a nut-free substitute for peanut butter, later filed for bankruptcy.

In 2016, officials said flour produced at a General Mills facility in Missouri may have infected as many as 63 people from two dozen states with E. coli.

In 2015, Chipotle Mexican Grill, a restaurant chain popular for its promise to offer high-quality and sustainably sourced food, found its reputation tarnished after 60 people from 14 states were sickened with E. coli. CDC officials could not identify what type of food was the source of the bacteria, but they said that majority of the sickened people said they ate food from Chipotle shortly before they became ill.

The company closed 43 restaurants in Washington state and Oregon after health officials linked an E. coli outbreak to six restaurants in the Northwest.

This article, originally posted on April 14, has been updated. 

Roberto A. Ferdman and Abha Bhattarai contributed to this article.

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