This summer's outbreak of the cyclospora parasite is on track to be the worst on record, with more recorded cases in the past few months than in all last year combined.
Though linked to fresh produce such as iceberg lettuce—prompting recalls of some salad greens, herbs and berries—investigators have struggled to pin down a source. The outbreak has sickened thousands of Americans, often with intense gastrointestinal symptoms.
To better understand cyclospora and its health risks, we asked UChicago Medicine physician Asst. Prof. David Zhang, a specialist in pediatric infectious disease; and the UChicago Medicine Medical Group urgent care medical director, Joseph Newberg*.
What is cyclospora, and how is it different from what most people associate with food poisoning?
Cyclospora is a parasite, not a bacteria or virus.
Unlike norovirus, a stomach virus that spreads easily, cyclosporiasis (the illness resulting from cyclospora infection) isn’t contagious. It comes from eating affected food.
Cyclospora is harder to eradicate than viruses and bacteria, which are more likely to be naturally flushed out by diarrhea.
What are the common symptoms of cyclosporiasis?
After entering the body, cyclospora lodges in the small intestine and causes watery diarrhea and these other symptoms:
- Loss of appetite
- Abdominal cramping and bloating
- Fatigue
- Low-grade fever
- Increased flatulence
How does public health track an outbreak like this, and what makes cyclospora so hard to trace?
Typically, the lab will report positive results and provide this information to the health department, which will initially conduct detailed interviews with the patients involved. They will ask about travel, food intake, restaurant visits, potlucks etc.
But it’s more difficult to identify the source of infections the longer the incubation period, and with cyclospora, it can be up to two weeks—it can be hard to remember what you ate weeks ago. Beyond that, the food system is very complex and includes many potential areas of contamination, including the farms and distribution networks, the various suppliers and retailers that make tracing this difficult, very laborious. Lastly, multiple outbreaks can happen at the same time from different sources and can stretch public health agencies even further.
However, since we know cyclospora thrives in certain climates and conditions, it is typically a summer illness. Certain vegetation is more likely to be the carrier, so they can usually narrow it down. The later in the outbreak the health department is notified, the greater the chance that the affected foods have made it into our groceries or restaurants, and the higher the numbers climb.
With no confirmed source, what should people do about fresh produce?
With no single food to avoid, it comes down to a few habits. Cooking is the most reliable step, as heating to at least 158 degrees Fahrenheit will kill cyclospora.
Washing alone won’t fully remove the parasite, but it is still important. Wash your produce thoroughly, rubbing items under cold water, using a colander for delicate produce and a scrub brush for root vegetables. Prevent cross-contamination by keeping produce separate from raw meat and cleaning cutting boards, knives and surfaces before and after food prep.
Be aware of recalls issued by the Centers for Disease Control and Prevention (CDC), the Food and Drug Administration (FDA) and other health officials: outbreaks have been linked to fresh produce including bagged salads, leafy greens, berries and herbs. And as always with food, keep your hands clean. Scrub with soap and water for at least 20 seconds before preparing food and before eating.
How long does cyclosporiasis last and how is it treated?
Symptoms usually start about two to 14 days after exposure and can persist for several weeks.
Most healthy patients will recover without antibiotics, but cyclosporiasis can sometimes cause complications such as dehydration, reactive arthritis, malnutrition or gallbladder inflammation.
UChicago Medicine can test for cyclospora. Positive results are reported to the public health department to help manage outbreaks.
What should you do if you have symptoms of cyclosporiasis? And when should you see a doctor?
It depends on how severe the diarrhea is. If you’re otherwise healthy and able to keep down fluids and electrolytes, it is best to let your body naturally flush out the cause. Make sure to drink plenty of water or an electrolyte drink to stay hydrated.
If your diarrhea lasts longer than two or three days, or you have more than six bowel movements per day, contact your healthcare provider for further guidance.
Seek medical care if you have severe diarrhea lasting more than two or three days, or if you can’t hold down food or liquids. UChicago Medicine offers walk-in and virtual urgent care across Chicagoland.
If you have recently traveled outside the United States, you should see a doctor. Anyone experiencing lightheadedness, shortness of breath, or weakness when standing should seek medical attention immediately.
Immunocompromised individuals and those with kidney problems face a higher risk of complications and should consult a doctor if diarrhea lasts more than a day or two.
What should you eat and drink if you have symptoms?
Hydration is key. Make sure you’re drinking water and electrolyte solutions to prevent dehydration.
When you do eat, stick to bland foods like white rice and clear soup broth, which are gentle on the body. Avoid heavy, greasy or sugary foods, as they may worsen symptoms.
Eat slowly, as consuming too much too fast will only keep things moving through your system.
You may consider taking Imodium (loperamide) to help slow diarrhea, but do not use it if your stool is bloody or black, or if you have a fever.
*Joseph Newberg, MD, is the Medical Director of Urgent Care for UChicago Medicine Medical Group and a UChicago Medicine Medical Group provider. UChicago Medicine Medical Group comprises UCM Medical Group, Inc., f/k/a UCM Care Network Medical Group, Inc., and UCM Medical Group Sub, LLC f/k/a Primary Healthcare Associates, S.C. UChicago Medicine Medical Group providers are not employees or agents of the University of Chicago Medical Center, the University of Chicago, UChicago Medicine Ingalls Memorial, UChicago Medicine Medical Group - Homewood, UChicago Medicine Dearborn Station or UChicago Medicine River East.
—This article originally appeared on the UChicago Medicine website.
