Cyclospora Infections: Are You at Risk?

Medically Reviewed by Michael W. Smith, MD on July 25, 2013
From the WebMD Archives

July 25, 2013 -- Cyclosporiasis, a stomach bug that's typically picked up from fresh produce, has sickened more than 285 people in 11 states, according to the CDC.

That makes it one of the largest outbreaks of cyclospora infection ever reported. "In recent years we haven't seen a big outbreak like this," says Monica Parise, MD, chief of the parasitic disease branch at the CDC.

Health officials are urgently trying to track down the source of the infection.

So far, Iowa with 138 cases, Nebraska with 70, and Texas with 66 are the hardest hit states. Georgia, Connecticut, New Jersey, Ohio, Illinois, Wisconsin, Minnesota, and Kansas each have reported between one and three cases. So far, 18 people have been hospitalized.

To find out more about this foodborne illness, WebMD reached out to Andi Shane, MD, MPH, a pediatric infectious disease specialist at Emory University in Atlanta, and Ann Garvey, DVM, MPH, deputy state epidemiologist with the Iowa Department of Public Health in Des Moines.

Here's what they told us about the current outbreak, symptoms of cyclosporiasis, and how the illness is diagnosed and treated.

What is cyclospora?

Cyclospora are single-celled parasites that mostly live in tropical environments. It has two life stages: One is an active organism, and the other is a dormant stage called an oocyst. When people swallow the oocyst, they become active in the body, causing uncomfortable gastrointestinal symptoms.

How does it get into food?

The dormant oocyst is excreted through human stool into the environment, where it can contaminate fruits, vegetables, or water, Shane says.

"Humans, as far as we know, are the only hosts for this organism. So what happens is farmworkers will get ill in the fields near fruits and vegetables, or they go to the bathroom and they don't wash their hands properly. They transfer the parasite onto the fruits or vegetables," Shane says.

What kinds of foods are usually affected?

Outbreaks in the United States are typically associated with fresh fruits and vegetables, according to the CDC. Fresh raspberries imported from Guatemala sickened more than 1,000 people in 20 states in 1996.

Other outbreaks have been associated with fresh basil, lettuce, and snow peas.

Does cooking or freezing eliminate the risk?

Yes. The CDC says commercially canned and frozen fruits and vegetables have never been implicated in an outbreak.

What about washing fruits or vegetables?

The FDA recommends washing all fresh fruits and vegetables, including fresh herbs and fruit that you plan to peel. As an extra step, the FDA also recommends drying all kinds of fresh produce with a paper towel to wipe away any residue that might still be clinging after a rinse.

That's an especially good move in the case of cyclospora oocysts. "Cyclospora can be really sticky and hard to wash off fruits and vegetables," Garvey says.

The CDC says bleach and other chemicals like iodine don't seem to kill cyclospora, so you can forget soaps and detergents.

How do you know if you're infected?

The telltale symptom of the infection is watery diarrhea that comes and goes. "About half of people have low-grade fevers. Some people feel like they sort of have a flu-like illness. There's a lot of gas, usually, too. It can last for several weeks," Shane says.

Among the cases in Iowa, Garvey says , the main symptoms are watery diarrhea for extended periods of time, weight loss, bloating, fatigue, and some vomiting. “Lots of people have lost their appetites and have experienced significant weight loss. These are all pretty consistent with classic symptoms."

People can be hospitalized for dehydration associated with prolonged diarrhea.

If you have diarrhea for several days or diarrhea that comes and goes, see your doctor. Also watch out for signs of dehydration, such as dry mouth and tongue, not urinating much, and dizziness. If you’re not able to keep water or other liquids down, see your doctor.

How is it diagnosed?

Diagnosis is difficult because you can have the infection for 2 to 14 days before you start to have symptoms. "You’re asking people to think about things they've eaten more than a week ago. That's really hard to remember, so that's why I think it's been really challenging for the CDC and FDA to figure out what the vehicle is," Shane says.

Also, cyclospora aren't present in the stool in high numbers, so doctors have to concentrate the sample before sending it to a lab. The lab test also requires a special staining of the specimen.

To help doctors identify sick patients quickly, the CDC is offering special remote diagnosis of suspected infections. They will do remote diagnosis from a digital image sent through email, Shane says.

How are cyclospora infections treated?

Bactrim, an antibiotic, is the standard treatment. "Most people, if they take a 7- to 10-day course of Bactrim, experience relief of symptoms," Shane says.

Are certain groups of people particularly vulnerable?

A lot of stomach infections affect the very young and the very old, but for cyclospora, the average age of infection is 44. Women are more likely to be infected than men, probably because they're more likely to eat the kind of foods that become contaminated with cyclospora, Shane says.

Show Sources


CDC: "Investigation of an Outbreak of Cyclosporiasis in the United States."

FDA: "Raw Produce: Selecting and Serving it Safely."

Herwaldt, B. The New England Journal of Medicine, May 29, 1997.

Andi Shane, MD, pediatric infectious disease specialist, Emory University, Atlanta.

Ann Garvey, DVM, deputy state epidemiologist, Iowa Department of Public Health, Des Moines.

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