LOS ANGELES (CBS News/CBSLA) – The Food and Drug Administration is looking into whether California is the source of a romaine-lettuce linked E. coli outbreak after nearly a third of the cases nationwide have been diagnosed in Los Angeles County.

Of the 32 cases across 11 states, nine of them are here in L.A. County, the L.A. County of Public Health Department reported Tuesday.

The 32 people have been infected with a strain of Shiga toxin-producing E. coli known as O157:H7, according to the public health department.

No deaths have been reported.

The Centers for Disease Control and Prevention has asked the public not to eat or purchase any romaine lettuce and to throw away any lettuce they have in their homes. Retailers have been asked to pull romaine lettuce off their shelves and restaurants have also been asked not serve it to customers.

Scott Horsfall, the CEO of the California Leafy Greens Marketing Agreement, told CBS News Wednesday that most of the romaine on the market when the outbreak began was grown in his state.

“Given the harvest cycle at that time, I think there’s a good possibility that it came from California, yes,” Horsfall said.

But he also said finding the exact farm will be difficult because it takes about two to three weeks for investigators to confirm an E.coli outbreak is underway.

“So by the time they’re actually doing trace-back, there is no packaging left, there’s no product left,” Horsfall said.

An important clue for investigators is the bacteria’s DNA. It’s very similar to the E.coli strain that caused a still unsolved outbreak in 2017.

“If you look at the map of illness onsets from last year, it is very similar to this recent outbreak….because these two are related, we have really more clues to go by now in terms of where people got sick and the timing involved,” Horsfall said.

The LADPH said it is working with the CDC to determine if any of the local cases have a connection which could help them find the source of the E. coli outbreak.

Symptoms of E. coli include bloody diarrhea and stomach cramps three to four days after eating contaminated food. While most patients will recover within a week, extreme cases can result in kidney failure, the county health department reports.

This is the second nationwide E. coli outbreak linked to tainted romaine lettuce this year. In April and May, and outbreak sickened at least 98 people across 22 states. That outbreak was linked to tainted lettuce out of Yuma, Ariz.

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