CHICAGO — A parasite causing “explosive diarrhea” has caused widespread panic across the country, adding new complexities to safe food handling at home and worrying diners about ordering the wrong leafy green at a restaurant. Health experts in Chicago say caution is warranted either way, but suggest considering several key factors before raising the alarm.

“For patients or individuals that have really serious immune problems or problems with their gut health, I think it’s reasonable to be really careful about what fresh produce you’re eating right now, regardless of if it’s at home or a restaurant,” said Emily Landon, UChicago Medicine’s executive medical director of infection prevention and control.

For Landon, this means avoiding fast-food chains and instead choosing to eat at home or at smaller, local restaurants, which she believes carry a lower risk because they handle a lower volume of food.

Cases of the cyclospora parasite are not uncommon in the summer months, she said, and while outbreaks of the current caliber are more rare, occasional cases are common.

The illness is spread through the fecal-oral route, which Landon admits sounds terrible. But almost all diarrheal illnesses work the same way.

“Things that grow in fields can get contaminated by poop from other animals, and sometimes produce can get indirectly contaminated if contaminated water is used to wash it off before it’s ready to be sent off. Imagine if you have a few things that are contaminated, and then they all get dunked into water together,” she explained.

For some foods like broccoli, berries, leafy greens and fruit with crevices, it’s especially difficult to fully wash off the fringy cyclospora.

While cyclosporiasis is not fatal, symptoms include bouts of explosive diarrhea that can last from days to several weeks, loss of appetite, bloating, increased gas and stomach cramps, nausea and sometimes vomiting.

As of Tuesday, Illinois had 216 reported cases of cyclosporiasis, according to the Illinois Department of Public Health. Of those, 96 individuals reported traveling outside of the U.S. and 95 acquired the illness domestically.

“At this point, no single source or cause of this increase has been identified, and there is no evidence of a large outbreak accounting for all or most of these cases. IDPH continues to work with the Centers for Disease Control and Prevention and other public health partners to look for trends,” a spokesperson for the department said in a statement Monday.

A spokesperson for IDPH told the Tribune on Tuesday that if consumers are concerned about getting cyclospora from dining out, they can select fruits and vegetables with peels or outer layers, such as avocados or sweet potatoes, or choose produce cooked to at least 158 degrees.

If cooking at home, the agency recommends following guidelines for safe food handling, including washing all fruits and vegetables under running water before eating, cutting or cooking, and scrubbing firm produce with a clean produce brush.

At least 34 states have reported cases of the illness since May 1, according to the CDC, with Michigan experiencing a particularly large outbreak, according to the Michigan Department of Health and Human Services.

Bethany Doerfler, senior clinical research dietitian at the Digestive Health Institute of Northwestern Medicine, said high-risk groups should opt for cooked vegetables. Other diners who are worried about catching the illness should ask where restaurants get their ingredients from before ordering.

“For the Chicago restaurant diner who still really wants a salad, it’s a reasonable question to ask your favorite restaurant — where are you sourcing your lettuce from?” Doerfler said. “Rather than limiting yourself across the board, rely on your restaurant to give you the information that makes you feel like you’re making a smart choice.”

Some local restaurants might offer hydroponically grown greens that may not carry the same risks as leaves grown on a large farm or ones that are commercially grown, she noted.

“Restaurants that are getting things from local farmers markets can tell you a little bit about how the lettuce arrives,” Doerfler added. “I think local greens could be a great option, like many microgreens and micro herbs grown in the Chicago area.”

Doerfler also suggested that consumers consider purchasing produce from farmers markets while the situation stabilizes. Not only is the farmers market supply chain significantly shorter, reducing handling time and cross-contamination risks, but shoppers can speak directly with growers to learn about how the crops were fertilized or watered.

Georgios Filiadis, emergency medicine physician at Silver Cross Hospital in New Lenox, said that while he sees patients with gastrointestinal tract issues daily, he hasn’t yet had a patient come into the ER with cyclosporiasis. He said he hopes it stays that way.

Filiadis said he’s worried about food consumed at outdoor summer picnics, as the Chicago area grapples with heat waves. The cyclospora parasite “thrives” in heat and humidity, conditions that allow the bacteria to divide and form spores, he said, so foods should be kept refrigerated when appropriate. And the only completely reliable way to kill cyclospora on contaminated food is through cooking it.

Still, health experts are wary of telling people what not to eat, said Landon. One of the trickiest facets of this cyclosporiasis outbreak is that health officials haven’t yet traced it back to a specific supplier, grower or type of produce.

“We really don’t know what is causing this, so avoiding everything that could possibly have cyclospora contamination is pretty much impossible,” said Landon.

The Washington Post reported Tuesday that federal and state health officials are investigating whether Taco Bell restaurants played a role in the cyclospora outbreak after some locations in the Detroit area posted notices that they were currently unable to sell lettuce, cilantro, onion, pico de gallo or guacamole.

“If I can really make a dietitian forward statement, I’d like to encourage people to use this opportunity to make other choices besides fast food,” Doerfler said. “Fast-food places are not known for their vegetables … so it’s reasonable to omit that until we know more.”

The Tribune reached out to Taco Bell and a number of fast-food chains and none could immediately be reached for comment.

Landon, from UChicago Medicine, wondered if the shortage of information could be an impact of staffing cuts at the Federal Drug and Food Administration, which has slashed the number of personnel responsible for administering routine food testing since the Trump administration took office.

“I worry that maybe some of the routine testing that may have identified these things is not happening as it used to,” she said.

Last July, the Centers for Disease Control and Prevention scaled back its FoodNet program, reducing the number of monitored pathogens from eight to just two — salmonella and E. coli. That change made federal reporting for cyclospora and five other pathogens optional.

Landon said health experts nationwide have warned that the loss of centralized data makes it significantly harder to spot multistate trends or identify contaminated food sources quickly.

“For instance, when you hear about E. coli, (officials) are like, ‘It’s in romaine lettuce, and it was found at this store in this state, and this is the product number, and so on,’” Landon explained. “And then you know to just throw away your food that is contaminated, right? Problem solved.”

But to get to those conclusions, local hospitals must conduct molecular diagnostic tests that simultaneously screen a single patient sample for multiple pathogens such as viruses, bacteria and parasites. Certain tests that come back positive are then reported to the state’s health department.

Afterward, a series of public health foodborne illness surveys are sent to infected persons to nail down the exact time frame that someone may have come in contact with a specific pathogen, like E. coli, by asking them to list everything they’ve consumed in a given number of days. Rigorous statistical analysis then points labs in the right direction.

Now, not only are there fewer people working in public health, but cyclospora itself is more chaotic to track down, Landon said. The cyclosporiasis incubation period is two to 14 days, longer than that for other diarrheal illnesses, she said, which makes it difficult to figure out what the true cause was.

“People often blame the last thing they ate before they started having symptoms, but in most cases it’s what they ate three to five days ago, or longer,” Landon said.

She said that until a cause is uncovered, individuals weigh the risks and potential outcomes when choosing food.

“I am loath to recommend that people not eat fresh fruits and vegetables in the summer because there’s so many benefits associated with eating fresh fruits and vegetables that are in season,” she added. “I am probably eating fewer salads this summer than I would, but I haven’t cut back on my berries.”

The treatment for cyclosporiasis is accessible and even in severe diarrhea cases, it usually goes away on its own, Landon noted.

“If you do start to feel sick, understand that it could be cyclospora, and know that most people are going to be just fine,” she said. “But if you’re getting dehydrated or having other problems or if you’re medically complex, then you probably want to reach out and get help from a doctor. There are treatments that we can use to shorten the course of illness and make it better.”

The most commonly cyclospora-contaminated foods, according to experts

Bagged lettuce: “Don’t buy those bags of lettuce that you’re unlikely to wash on your own,” Landon said. “The surface-area-to-volume ratio of lettuce used in those bags is a problem.” The individual lettuce pieces are more likely to be directly exposed to potential bacteria, compared with a compact head of lettuce. Instead, she suggests buying whole heads of lettuce, discarding two layers of outer leaves, and washing the inner leaves.

Boxes and bags of arugula: “Anything where you have individual leaves — like all arugula, which just doesn’t come any other way — you should avoid right now, or you really need to clean them,” Landon said. “But the problem is they’re not as easily cleanable, and you certainly can’t be cleaning them with super hot water because they get soggy and lose their crunch.” Doerfler, the Northwestern dietitian, recommends opting for microgreens that are grown hydroponically in controlled environments. They can be more expensive, though.

Raspberries: “Raspberries are really hard to clean off, and the parasite things hang on to the bumpy surface,” Landon said. Landon said she is still eating raspberries and strawberries, despite the risks, but she is washing them meticulously.

Cilantro, parsley, basil: Wash each individual leaf before use — fan them out under water, rub between thumb and fingers thoroughly and pat dry on a clean paper towel.

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