A multi-state outbreak of the E. coli virus, linked to romaine lettuce, has killed one person in California, the CDC has reported. The outbreak began in March and has spread to at least 25 states with over 100 cases reported.  

Officials believe that the tainted lettuce was grown in the Yuma, Ariz., region, so the CDC has warned both restaurants and consumers to steer clear of romaine lettice unless they can confirm that the lettuce was not grown in that area. Infections have been traced back to both whole-head lettuce and bagged lettuce. Some infections have been linked to grower Harrison Farms, who provided the whole-head lettuce, but officials have not yet identified the supplier/suppliers responsible for the chopped, bagged lettuce. The CDC has urged extra caution since product labels often do not identify growing regions.

Symptoms of E. coli typically start three or four days after consuming the bacteria. Victims may experience severe stomach cramps, diarrhea, and vomiting. Most people recover within five to seven days — however, it’s possible for others to develop hemolytic uremic syndrome, a type of kidney failure that can be life-threatening. In this current outbreak, 52 people have been hospitalized, with 14 of those people developing hemolytic uremic syndrome. The CDC reports that the bacteria train identified in this outbreak is particularly powerful, which explains the higher-than-normal hospitalization and complication rates.

The FDA says that it has received confirmation from the Arizona Leafy Greens Marketing Agreement administered by the Arizona Department of Agriculture that romaine lettuce is no longer being produced and distributed within the Yuma growing region. While this reduces the potential for exposure to contaminated product, the lettuce’s 21-day shelf life means that it’s unclear if romaine lettuce from the Yuma region is still in the supply chain.

This outbreak is the largest in the U.S. since 2006, after an E.coli outbreak linked to spinach sickened 199 people and killed three.