Foodborne Illness Outbreak: Cyclospora


Cyclospora parasite
Magnified microscopic image, courtesy of Stanford University

Federal and state agencies are working together to determine which foods are responsible for an outbreak of diarrheal illness that has affected almost 400 people in 11 states. Prepackaged salad mix has been identified as responsible for outbreaks in Iowa and Nebraska, but it is not known whether outbreaks in other states are also linked to bagged salad.

The illness, cyclosporiasis, is an intestinal infection caused by the parasitic one-celled protozoan, Cyclospora.  The Centers for Disease Control and Prevention (CDC), the Food and Drug Administration (FDA) and state health agencies are determined to identify the source of contamination and remove it from the marketplace.  Meanwhile, consumers can take steps to avoid this latest foodborne outbreak.

Cyclospora Life Cycle

According to CDC, people contract cyclosporiasis when they ingest food or water that is contaminated with feces from infected people; in the case of food, contamination may occur when food handlers neglect proper hand hygiene or when farm irrigation systems become contaminated. Contamination can also occur when water used for washing or freshening is contaminated.Cyclospora is common in tropical and developing countries. It was introduced in the United States in the early 1990’s, but was confined primarily to adults returning from a visit to countries where this parasite is endemic.   More recently this disease has been traced to food ingested in the US.  Previous US outbreaks of cyclosporiasis involved raspberries, basil, lettuce and snow peas. 

Cyclospora have two life cycle stages:  dormant and active.  Cyclospora are dormant in stool, existing as thick-walled structures known as oocysts (egg-like structures).  These oocysts mature in the environment and once mature they can infect the digestive tract after ingestion, where they begin to initiate the disease process.  Diarrhea may appear about one week after eating contaminated produce.  Other common symptoms are appetite loss, stomach cramps/pain, bloating, increased gas, nausea and fatigue.  Vomiting, body aches, headache, fever and other flu-like symptoms may also occur.

Tips on Avoiding Cyclosporiasis

  • Practice safe food handling
    • Thoroughly wash all fresh fruits and vegetables (even those that you are planning to peel) before eating. If possible, rub dry with clean paper towels as Cyclospora may stick to food surfaces.
    • Wash, rinse and dry hands and food-contact surfaces with warm, soapy water; CDC notes bleach and iodine do not seem to kill Cyclospora.
    • Separate raw foods, such as produce and raw meats, from other foods to avoid cross-contamination.
  • Know your options
    • Commercially canned and frozen fruits and vegetables have never been implicated in a Cyclospora outbreak; cooking and freezing may eliminate or reduce the risk, according to Web MD.
  • Groups affected
    • According to Web MD, the average age of Cyclospora infection is 44; women are more likely to become infected than men, possibly because of the kind of foods that become contaminated.
    • People in poor health or who have a weakened immune system may be at a higher risk for severe or prolonged illness. 
  • Treatment
    • According to CDC, most people with healthy immune systems will recover from cyclosporiasis without treatment.  If untreated, however, the illness may last for a few days to more than a month, and relapse is common.  Antibiotics are prescribed when treatment is indicated.

We will follow the progress of the expert disease detectives and keep you updated on the Cyclospora outbreak.

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