How to avoid getting the ‘diarrhea parasite’… experts reveal which foods put you most at risk and the ones that are safe to eat

A parasitic stomach bug from a mysterious source has sickened thousands across the US, leaving Americans on their own to figure out what’s safe to eat and how to protect themselves. 

Cyclosporiasis cases across the country continue to climb at a breakneck pace, and public health officials are scrambling to pinpoint the source as the case count surpasses 5,800 confirmed infections – with thousands more under review.

Michigan alone has seen more than 4,300 cases, compared to its usual yearly average of fewer than 50. Hospitalizations have risen to 102.

Cyclosporiasis is caused by the Cyclospora parasite, which is linked to foodborne outbreaks and not considered contagious from person to person. However, it is a hardy organism that adheres easily to the surfaces of fresh produce and fruit – and it is difficult to kill off.

The intestinal illness causes symptoms to emerge two days to two weeks after exposure and they include prolonged watery diarrhea, stomach cramps, nausea, fatigue, loss of appetite and weight loss.

It is treatable with antibiotics, but without treatment, it can last weeks and cause dehydration. About one in 11 cases has required hospitalization; no deaths have been reported. 

‘Foodborne illnesses like Cyclospora wreak havoc on the gastrointestinal tract, causing large microbiome imbalances that can mean long-lasting GI symptoms,’ Dr Mark Pimentel, a gastroenterologist at Cedars-Sinai Hospital, told the Daily Mail.

The parasite spreads through the fecal-oral route, typically contaminating produce at the farm level through infected human feces. 

Unlike other foodborne pathogens, cyclospora doesn’t come from farm animals and humans are its only natural host. 

‘Most people think contamination like this happens because of a dirty surface they can see, or a restaurant with shady practices, but cyclospora doesn’t follow that rule,’ Texas-based food safety expert Jason Reese told the Daily Mail.

The parasite’s oocysts – the egg-like stage of the parasite excreted in feces – must mature in the environment for seven to 15 days before contaminated water or soil can carry them to produce.

Once cyclosporiasis enters the supply chain, it’s undetectable. 

There is no smell or visible signs of contamination on the produce in the grocery store or on your restaurant plate.

Investigators are zeroing in on lettuce and salad greens as potential culprits, as Michigan health officials have noted that lettuce regularly comes up in case interviews.

However, the exact origin remains a mystery, leaving consumers wondering: What’s safe to eat? 

The riskiest foods for cyclosporiasis 

While health officials stress that the vast majority of produce remains safe, certain items carry significantly higher risk during this outbreak. 

Bagged salads and salad kits top the list of foods to avoid right now, even those that claim to be ‘pre-washed.’ 

‘The riskiest items are bagged salads and kits, herbs like cilantro and basil, green onions, snow peas, leafy greens and raspberries,’ Reese said. 

Bagged produce has extra risk. The chopping, mixing, and packaging process creates more opportunities for contamination and the ‘pre-washed’ label offers no guarantee during an active outbreak. 

Reese said: ‘It means it was washed before it was packed, but anything could have happened to it in the supply chain before or after that washing.

‘Some of the most serious outbreaks linked to produce that have occurred in recent times include pre-washed and packaged greens.’

Fresh herbs – especially cilantro and basil – are also high-risk. Their delicate leaves make thorough washing difficult, and they are often eaten raw. 

Because the parasite is invisible and odorless, contaminated produce shows no signs of spoilage. Cyclospora is also ‘sticky,’ and its oocysts have surface proteins that make them adhere easily to produce. 

Foods with textured surfaces, especially fruits like raspberries and blackberries, can trap oocysts in their crevices, making them especially hard to remove. 

Green onions and snow peas are also on the warning list. While washing and rubbing their surfaces can help, cooking them is far safer.

Dr Steven Goldberg, a family medicine physician based in Kentucky, told the Daily Mail: ‘Cyclospora is overwhelmingly linked to fresh produce; specifically items that are eaten raw and are difficult to wash thoroughly.’ 

But even standard washing is not enough. 

‘What makes this most concerning is that washing your produce with just water doesn’t fully remove or kill this parasite,’ Reese said. 

‘[Cyclospora’s] outer shell hangs onto crevices on the surface, and that makes it resistant to standard produce washing practices.’

Safer options

Health officials and food safety experts emphasize that you don’t need to swear off produce entirely – you just need to make smarter choices.

Whole heads of lettuce are a safer alternative to bagged salad mixes. 

Reese explained: ‘If you’re going to eat raw produce, always choose whole heads of lettuce instead of the pre-washed bagged options and throw out two to three layers of the outer leaves before thoroughly washing all inner leaves under running water.’

Michigan health officials similarly advise consumers to ‘buy whole heads of lettuce, discard the outer layers and thoroughly wash what’s left.’

Goldberg added: ‘Frozen and canned fruits and vegetables are safe alternatives. The processing involved – blanching, cooking and freezing – effectively eliminates the parasite.’

Cooked vegetables are the safest bet of all, Reese said. Heat kills the cyclospora parasite at 158 degrees Fahrenheit, according to gastroenterologists. 

Produce with a peel, such as bananas, avocados, oranges, melons, cucumbers and pineapples, have a natural barrier; just wash the outside before cutting. 

Peeled items like carrots, potatoes and apples are also safer, as peeling removes the contaminated surface layer.

How you can avoid infection

Proper washing is essential, but it will not remove everything.

‘People should thoroughly wash fresh fruits and vegetables under water before eating, even if their produce looks clean,’ Dr Alan Bulbin, director of infectious disease at Catholic Health’s St. Francis Hospital, told Daily Mail.

With herbs, ‘you have to separate all leaves and wash them under running water,’ Reese added. 

Snow peas and green onions need washing and rubbing on the surface. Even melons and cucumbers ‘need to be scrubbed on the outside with a produce brush and running water,’ he continued.

Use running water, not a basin. One of the most common mistakes is rinsing produce in a basin of water. 

‘None of the hacks involving using vinegar or baking soda to wash fruits and veggies, soaking them in saltwater, lemon juice or any other similar trick has proven to be more effective than plain old tap water in fighting pathogens,’ Reese said. 

He does not advise using soaps and bleach as they can ‘get absorbed by the porous structure of fruits and veggies and become poisonous to ingest.’

And watch out for cross-contamination. 

‘People rinse their food very carefully but put it on a cutting board that was used yesterday while preparing dinner, or use a knife they used on raw meat just a minute ago. Always use clean cutting boards and utensils when preparing produce,’ he added. 

Keep unwashed produce separate from ready-to-eat foods and raw meat, poultry or seafood.

Especially important now, Reese noted, are hand washing and sanitizing: ‘[It] should be in full force in your kitchen.’