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- Cyclosporiasis infections are surging this summer.
- Extreme diarrhea is a hallmark sign of the parasitic infection.
- Health officials don’t yet know the source of the outbreak, but previous outbreaks have been linked to fresh produce.
Cases of cyclosporiasis—a parasitic infection that can cause severe diarrhea—have surged this summer.
The Centers for Disease Control and Prevention confirmed 843 cases and 86 hospitalizations across 31 states since May 1, but the true number is likely much higher. The agency noted that states have reported case counts not yet reflected in the national data. (As of Friday, Michigan alone, for example, had reported 1,562 cases.)
While cyclosporiasis cases typically increase during the warmer months, the CDC said multiple states have seen more cases over the past two weeks than during the same period last year.
Health officials are still working to identify the source of the outbreak, but past cases have most often been linked to fresh produce. Here are nine things to know about this recent outbreak, including how to limit your risk.
1. The source of the outbreak is still unknown
Although the Midwest and Northeast appear to be the hardest hit, cases have been identified in states ranging from California and Nebraska to Vermont. So far, public health officials have not confirmed how this outbreak began.
To investigate a cyclosporiasis outbreak, health officials interview patients and trace the foods they ate during the illness’s incubation period, which is the time from exposure to symptom onset.
But cyclosporiasis can be difficult to track because symptoms may not appear for up to 14 days after infection, and by then, many people can no longer remember what they ate.
According to Don Schaffner, PhD, department chair, distinguished professor, and extension specialist in food science at Rutgers University, the genetic tools available to trace cyclospora, the parasite that causes cyclosporiasis, are another limitation for investigators.
“The CDC has some genetic fingerprinting techniques for the organism, but it’s not nearly as precise as whole-genome sequencing,” he said. “So linking up these cases is challenging.”
2. Outbreaks are usually linked to fresh produce
According to the CDC, cyclospora spreads when people consume food or water contaminated with feces containing the eggs of the parasite. Person-to-person spread is unlikely because it takes about one to two weeks for contaminated feces to become infectious.
Previous cyclosporiasis outbreaks have stemmed from fresh produce, such as:
- Cilantro
- Basil
- Leafy greens including romaine, mesclun, watercress, and salad mix
- Raspberries
- Blackberries
- Sugar snap peas
- Snow peas
Until officials know more about the current outbreak, you shouldn’t assume any specific food is responsible. According to Schaffner, there may even be multiple unrelated outbreaks occurring at the same time, given that some states have reported far more cases than others.
3. Washing produce is always a good idea, but it’s not a silver bullet
It’s always a good idea to wash your produce. However, rinsing fruits and vegetables alone won’t completely eliminate the risk of cyclosporiasis because the parasite can still cling to food.
To increase your chances of removing it, wash produce in water that’s warmer than the produce itself, recommended Martin Bucknavage, a food safety specialist who recently retired from Penn State.
“We want that produce item to open up rather than to constrict,” he said, “so if there are any parasitic organisms there, they’re more likely to give it up.”
For heavily creviced foods, like raspberries, Shruti Gohil, MD, a board-certified specialist in infectious diseases and associate medical director of epidemiology and infection prevention at UCI Health, suggested submerging the food in water and swishing it around with your hand. Then, drain and repeat a few times.
Some people like to wash produce with a little vinegar or baking soda mixed into the water, but experts say there’s no evidence that either is effective against cyclospora.
It’s also important to wash your hands with soap and water before and after handling raw fruits and vegetables.
4. Symptoms usually don’t start right away
You might be used to food poisoning symptoms beginning within hours of eating contaminated food. But symptoms of cyclosporiasis can take a lot longer to show up—anywhere from two days to two weeks after infection.
As Bucknavage pointed out, many people may not seek medical attention for a symptom like diarrhea “until it doesn’t go away for days and days.” That delay is part of what makes these outbreaks so hard to trace. If you suspect you have cyclosporiasis, it’s worth getting tested as soon as possible.
5. Diarrhea is a tell-tale sign
If you have cyclosporiasis, sudden, watery diarrhea is often the first clue. That said, you might experience other symptoms, including:
- Loss of appetite
- Weight loss
- Vomiting
- Flu-like symptoms, including headache, fever, body aches, and fatigue
- Stomach cramps and pain
- Bloating
- Gas
Your symptoms may vary depending on your immune function, Gohil said. “You might feel better for a little while, and then it’ll relapse,” she said. “Or you never quite feel better, and you have this chronic diarrhea thing where your body kind of controls it, so it’s not explosive diarrhea anymore and your bloating is kind of gone, but you’re still not feeling quite right for weeks.”
6. Most healthy people recover, but some people should seek care sooner
Cyclosporiasis is not usually fatal. However, Gohil noted that people who are immunocompromised, younger than age 6, older than age 65, or pregnant may face a higher risk of severe symptoms and longer recovery periods.
To Gohil, dehydration is one of the top concerns, especially among immunocompromised patients. “Dehydration can never be underestimated in its impact on the body and the electrolyte disturbances,” she said.
7. It’s treatable
No one enjoys intermittent bouts of diarrhea, so if you suspect you’ve been infected, it’s worth seeking treatment—even if your risk of complications is low. People whose symptoms clear up over time can still experience relapses for weeks after exposure.
Typically, your doctor will start by ordering a stool test to confirm whether you have cyclosporiasis. If you do, they can prescribe a specialized antibiotic like Bactrim. “It’s a generically available drug—a very old drug we have lots of experience with,” Gohil said. “So I would consider [cyclosporiasis] easy to treat.”
8. You can keep eating fresh fruits and vegetables, but watch for news alerts
Public health officials have not recommended against eating fresh produce. Instead, the best way to reduce your risk is to practice safe food handling and monitor updates from health officials.
If you’re concerned about the water in your area, Schaffner recommended avoiding lake water and watching for updates from your local municipality.
“Situations like this point out the importance of having a strong public health system,” Schaffner said. For now, he added, “I would just encourage people to be vigilant and aware. Follow the news.”
