The source of a multistate Escherichia coli O157:H7 outbreak announced 3 days ago appears to be chopped romaine lettuce from the Yuma, Az., growing region, the US Centers for Disease Control and Prevention (CDC) said today.
Since the CDC's initial announcement on Apr 10, illnesses involving 18 more people from 9 states have been added to the outbreak, bringing the total to 35 cases in 11 states.
Interviews yield key clues
After interviewing sick patients, investigators found chopped romaine is the likely culprit. Of 28 people interviewed, 26 (93%) had eaten chopped romaine the week before their symptoms began. The CDC said the level was significantly higher than the 46% of healthy people who ate romaine the week before they were interviewed.
Most of the sick patients reported eating salad at a restaurant, and chopped romaine was the only common ingredient identified among the salads eaten. The restaurants used bagged chopped romaine to make the salads. "At this time, ill people are not reporting whole heads or hearts of romaine," the CDC said.
Trace-back investigations to determine the source of the chopped romaine the restaurants have yet to turn up a specific grower, distributor, or brand, but the early investigation suggests it came from the Yuma, Az., growing region. An investigation to further narrow the source is still under way.
Three patients have serious kidney complication
Of the 35 patients linked to the outbreak so far, 22 were hospitalized, including 3 with hemolytic uremic syndrome (HUS), a potentially fatal kidney complication. No deaths have been reported.
Illnesses began in the middle of March, with Mar 31 as the latest illness onset. The CDC said infections that occurred after Mar 27 might not have been reported yet, due to the time lag between symptom onset and when the case is reported.
Patient ages range from 12 to 84, and 69% of patients are female.
The CDC said the current outbreak isn't linked to an E coli event linked to leafy greens that was reported in late December, which sickened 25 people from 15 states, plus 42 from 5 Canadian provinces. The E coli O157:H7 in the earlier outbreak had a different DNA fingerprint.
Safety steps for restaurants, retailers, consumers
The CDC is urging restaurants and retailers not to serve any chopped romaine, including salad mixes, from the Yuma, Az., region. Also, it advised the two groups to ask suppliers about the source of chopped romaine lettuce.
Consumers who have chopped romaine in their homes, including salads and salad mixes, should not eat it and should throw it away, even if no one got sick. Before buying chopped romaine in a store or eating it at a restaurant, consumers should confirm that it is not from the growing region implicated in the outbreak.
Apr 13 CDC outbreak update
Apr 13 CDC advice for consumers
Apr 11 CIDRAP news story "CDC: E coli outbreak sickens 17 in 7 states"