On the 2018 list of “things that are a bad idea to shove in your face,” raw sprouts from Jimmy John’s may be up there—right behind Tide laundry pods.

The Centers for Disease Control and Prevention and the Food and Drug Administration announced late Friday that a multistate outbreak of Salmonella is linked to raw sprouts served at the sandwich chain’s restaurants in Wisconsin and Illinois. While sprouts in general are a well-established source of foodborne illnesses linked to many dozens of outbreaks in recent decades, Friday’s announcement marks at least the seventh time since 2008 that raw sprouts at Jimmy John’s specifically have caused outbreaks.

In response, Jimmy John’s on Friday ordered sprouts off the menu at all 2,727 of its restaurant. The company called the move a “precautionary measure.”

“Food safety and the welfare of our customers are our top priorities and not negotiable in our business,” Jimmy John’s owner and president, James North, said in a statement. He went on to say that Jimmy John’s was working with state health departments and federal agencies in their ongoing investigations into the outbreak. So far, the outbreak appears to be linked to contaminated clover sprouts, possibly purchased from two growers in Minnesota, according to Food Safety News.

The CDC reported that eight people have been sickened in three states: two people in Illinois, one in Minnesota, and five in Wisconsin. No one has died or been hospitalized due to the infections. The first case was reported December 20, and the most recent report came in on January 3. But the agency noted that more recent cases may not yet be counted due to a lag in reporting.

Due to the government shutdown, no one was available at the CDC to respond to media requests. Ars reached out Jimmy John’s but did not immediately receive a response.

The consumers affected in the outbreak were all infected with a strain of Salmonella Montevideo, which has become a more common type linked to outbreaks around the globe recently. In earlier outbreaks, it was been linked to contaminated poultry. In general, Salmonella causes fever, abdominal cramps, and diarrhea. If the symptoms worsen and/or the infection spreads to the blood, it can become life-threatening and require hospitalization. The situation is more dangerous in young children, the elderly, and people with weakened immune systems.

Why sprouts?
Sprouts in general—including alfalfa, clover, radish, and mung bean—are a risky food with a long history of causing Salmonella and E. coli outbreaks. The reason for this is a combination of factors. First, prior to sprouting, the seeds offer a safe haven for bacteria, which steadfastly cling to the outside and even the inside of the seeds. Seeds can pick up the germs prior to being harvested in the field, where they may be exposed to manure fertilizers, contaminated irrigation water, or other sources, such as feces from wild animals. Growers now use various sanitation methods and washes to reduce contamination.

But they’re not enough. Even with washes of the bleaching agent calcium hypochlorite, no sanitation method has proven 100-percent effective at ridding seeds of pathogens.

Once harvested, the next step can make contamination worse. Producers take those seeds and sprout them in warm, humid conditions—which E. coli and Salmonella love. In those conditions, the bacteria grow exponentially, jumping orders of magnitude in just a couple of days. From there, the sprouts are typically washed with water, as is done with other produce. This only slightly reduces the bacteria load. And then they’re often eaten raw in sandwiches and salads.

Since 1998, the CDC has counted about 56 outbreaks and more than 1,800 illnesses linked to raw or lightly cooked sprouts, most involving Salmonella or E. coli. In 2010, Walmart quietly stopped selling sprouts and Kroger grocery stores followed in 2012.

“Sprouts present a unique challenge because pathogens may reside inside of the seeds where they cannot be reached by the currently available processing interventions,” Payton Pruett, Kroger’s vice president of food safety, said in a news release at the time. “Out of an abundance of caution, the Kroger family of stores will no longer sell fresh sprouts or procure other foods that are produced on the same equipment as sprouts,” he explained.

Piling on the outbreaks
Since 2008, sprouts from Jimmy John’s have been linked to at least seven multistate outbreaks, according to food safety law firm Marler Clark. That includes as 2009 Salmonella outbreak that sickened 256. After a 2011 E. coli outbreak linked to its sprouts, the chain announced it was permanently cutting out the offending produce.

But, in 2012, the company announced sprouts’ return. Jimmy John’s had added a warning to its online ordering that stated: “The consumption of raw sprouts may result in an increased risk of food borne illness and poses a health risk to everyone. Click ‘Yes’ if you understand the potential risks or ‘Cancel’ if you’d like to continue without adding sprouts.”

Though Jimmy John’s is currently not serving sprouts at any of its stores, the company made clear that the sprout-suspension is just temporary. And for some Jimmy John’s fans, sprouts can’t make their return fast enough. @NatashaDugg tweeted to the sandwich maker “why did you guys discontinue the sprouts?? i’m so mad i walked out the place.”

The US Department of Health and Human Service’s Food Safety suggests that consumers can reduce their risks by cooking their sprouts or requesting that restaurants—such as Jimmy John’s—don’t add them to your food. But, the agency warns, that because of the risk of infections, “children, the elderly, pregnant women, and people with weakened immune systems should avoid eating raw sprouts of any kind.”