Pooping lettuce at Wendy's remains prime suspect in just-doubled outbreak

Enlarge / An old-fashioned Wendy's burger. Romaine lettuce on Wendy's burgers is believed to be the cause of the outbreak. Getty | Francois Doyen

A multi-state outbreak of E. coli O157 linked to romaine lettuce on Wendy's burgers has more than doubled since last week, according to an update from the Centers for Disease Control and Prevention.

The number of cases now stands at 84 and spans four states: Indiana (6), Michigan (53), Ohio (23), and Pennsylvania (2). That's up from last week's case count of 37 in the same four states. Currently, at least 38 of the sick people have been hospitalized. Eight of those people, all in Michigan, developed a severe and life-threatening type of kidney failure called hemolytic-uremic syndrome (HUS), the CDC reports. No deaths have been reported. So far, the sick people are between 5 and 94 years old, with a median age of 24.

Due to reporting delays, the CDC warns that "the actual number of sick people in this outbreak is likely higher than the number reported, and the outbreak may not be limited to states where illnesses are known ."

As before, the main suspect in the outbreak continues to be romaine lettuce, which Wendy's uses exclusively on burgers and sandwiches (the fast-food chain uses different leafy greens for its salads). The CDC notes that of the 62 affected people who were interviewed, 52 (84%) said they had eaten at Wendy's the week before falling ill.

Lethal lettuce

In a statement last week, Wendy's said it was cooperating fully with the CDC's investigation. "Although the CDC has not yet confirmed that a specific food is the source of this outbreak, we have taken the precaution of discarding and replacing sandwich lettuce at select restaurants in this area," Wendy's said. "The lettuce we use in our salads is different and unaffected by this action. As a company, we are committed to our high standards for food safety and quality."

As Ars pointed out, Escherichia coli O157:H7, produces Shiga toxin, which is toxic to cells and can shut down a cell's protein production. Shiga toxin can cause serious illness, including hemolytic uremic syndrome (HUS), which affects eight people in this outbreak. In HUS, the toxin enters the blood and leads to the mechanical breakdown of red blood cells and acute kidney injury. Although no deaths were reported in this outbreak, HUS can be deadly, and E.coli outbreaks linked to contaminated lettuce have been fatal in the past.

The CDC notes that "investigators are working to confirm whether romaine lettuce is the source of this outbreak and whether romaine lettuce served at Wendy's restaurants has been served or sold at other businesses." And the agency notes that it "does not advise people to avoid eating at Wendy's restaurants or to stop eating romaine lettuce."

But, E. Romaine contaminated with coli would not be a surprising confirmation. Lettuce - and salads in general - have been the source of a series of similar outbreaks in recent years. And while it's not always clear exactly how gut-killing bacteria enter lettuces, the culprit is often contamination from livestock manure in cultivated fields.

Producing shigatoxins E. coli are excreted through the intestines of animals, particularly cattle. In a traceback investigation of an E. coli involving contaminated romaine lettuce, investigators concluded that manure runoff from a high-density cattle farm upstream of more than 100,000 cows had contaminated canal water that could have been used for irrigate lettuce crops. This 2018 outbreak sickened at least 210 people in 36 states, sending 96 to hospital, causing...