Preventing Cyclospora Infection

How to protect yourself from cyclosporiasis this summer

You've packed the picnic with healthy salads and fruit — and a week later, you can't leave the bathroom. For Pennsylvania families, this summer's abundance of fresh produce might come with an invisible risk: Cyclospora, a microbe that can turn a healthy meal into weeks of misery.

Cyclospora cayetanensis is a single-celled parasite that infects the small intestine when people eat or drink contaminated food or water. The parasite can't be seen, smelled or tasted — and it's remarkably tough to destroy. Even routine chemical disinfection methods like chlorine or iodine treatment won't kill it. Cases peak between May and August, when fresh produce is tastiest and hot weather makes a salad a great choice for dinner.

While there are official case numbers reported by government agencies, many U.S. cases go undiagnosed because testing for Cyclospora isn't routinely done in American labs. So numbers are likely higher.

Stanley Martin, MD, an infectious disease specialist at Geisinger, helps patients understand this parasitic illness and practical steps to cut your risk. Learn how Cyclospora spreads — and what you can do to stop it.

“For those preparing food for young children, the elderly or those who are pregnant or with suppressed immune systems, it’s especially important to be aware,” says Dr. Martin.

What is a cyclospora infection?

Cyclosporiasis is the intestinal illness caused by the Cyclospora cayetanensis parasite. It spreads in contaminated food or water. The parasite doesn't spread directly from person to person — it needs time outside the body before it can infect a new person. Cyclospora have different phases of their life cycle including a microscopic egg-like oocyte, which takes a ride into your gut through food. Once in your intestine, they mature and make you sick.

What foods carry Cyclospora?

Historically, outbreaks in the United States have been linked to fresh produce including:

Basil
Cilantro
Italian parsley
Mesclun lettuce
Pre-packaged salad mixes
Raspberries
Snow peas

Cyclospora symptoms, diagnosis and treatment

Symptoms typically begin about 7 days after exposure. Most people have:

Watery, explosive diarrhea: Frequent and sometimes forceful bowel movements are the hallmark sign — more than 3 times a day in many cases.
Stomach cramps and bloating: Many people describe feeling uncomfortably full, even without eating — a feeling that can persist all day.
Loss of appetite and fatigue: It's common to feel very tired and have little interest in food.
Nausea, vomiting and low-grade fever: Some people also have body aches, headaches and other flu-like symptoms.

See your doctor if you have watery diarrhea that lasts longer than 3 to 5 days — or longer than 2 days if there's a known outbreak in your area.

“Without treatment, the illness can last from a few days to more than a month — and symptoms often calm down and then return,” says Dr. Martin. “Even for people with normal immune systems, it could take up to 6 weeks to resolve on its own.”

For people with compromised immune systems — including those on chemotherapy, organ transplant recipients and people living with HIV — symptoms may not go away without treatment.

Diagnosing cyclosporiasis

You may have eaten food contaminated with the parasite anywhere from 2 days to 2 weeks before you get sick. That can make it hard to learn how you caught it.

If you have a long bout of diarrhea, your doctor may test you for the parasite. It’s not included in standard testing.

“You may need to be tested more than once because the amount of parasite in your stool can increase and decrease,” says Dr. Martin.

Treatment

Many healthy people recover from infection without treatment, although they may have repeated rounds of diarrhea for several weeks. There are no vaccines against cyclosporiasis, but the drug trimethoprim-sulfamethoxazole (TMP-SMX) can treat it.

However, cautions Dr. Martin, “If you’re allergic to sulfa, you shouldn’t take this medication.”

How to prevent cyclospora infection

The good news: There are concrete steps every household can take. Cyclosporiasis prevention requires safe food handling and awareness.

The best way to kill Cyclospora is heat

Heat is the only way to completely kill Cyclospora. Cooking fruits and vegetables up to 158°F (70°C) or higher kills the parasite and is the gold standard to protect your family. Canning your summer vegetables and fruits? You’re good to go!

Wash your hands, produce and utensils to help prevent infection

The delicious but delicate fruits of summer are hard to skip. Take these steps to decrease — but not eliminate — your risk of getting the parasite.

Wash your hands: Before and after handling produce, wash your hands with soap for at least 20 seconds, and of course after using the bathroom.
Scrub all fresh produce: Wash fruits and vegetables before cooking or eating — even items with a skin you don’t eat.
Scrub the outsides before slicing or peeling: If you’re going to slice or peel produce like melons and cucumbers, rinse the outsides first to keep the parasites from sticking to the knife and contaminating the pieces.
If you can, peel the skin: Removing the skin from fruits and vegetables can help after you rinse them thoroughly.
Trim damaged spots: Cut away bruised or damaged areas before eating.

Try rinsing in vinegar and water to remove Cyclospora

A recent study looked at what washing techniques were best to clean berries, which are often linked to this type of infection. Cyclospora have an especially sticky outside that helps them cling to fruits and vegetables.

Rinsing berries under running water for 1 minute removed about half of the parasites — much more on smooth-skinned blueberries and less on bumpy, fuzzy raspberries.

The study found if you dunked the berries in 1 part vinegar and 3 parts water in a bowl, and then swished it around, it worked much better to remove Cyclospora. Whether that was because of the vinegar or the swishing, the scientists couldn’t say.

Be mindful of water and swimming

Usually, the parasite thrives in tropical or subtropical climates far from Pennsylvania. But closer to home, it’s possible to pick it up if you swim in a pool with infected people. It takes so long to get sick, people can have the parasite and not realize it.

“Chlorine and other pool chemicals don’t kill it,” says Dr. Martin.

And avoid drinking from untreated natural water sources like lakes and rivers. There’s a real chance invisible parasites and bacteria lurk in that seemingly crystal-clear water.

Don’t skip your vegetables and fruits

“For most people, the health benefits of eating fruits and vegetables are greater than the risk of the parasite,” says Dr. Martin. “If you aren’t a young child or a senior or you don’t have a compromised immune system, you should still eat vegetables and fruits with careful washing and awareness.”