Cyclospora Outbreak May Have Peaked Already

Cyclospora parasite and its human-linked life cycle.
Cyclospora parasite and its human-linked life cycle.

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A new stomach bug has arrived in the USA — but it might already be on its way out.

As of Friday afternoon, the Centers for Disease Control and Prevention had received notifications of 285 cases of Cyclospora infection — about twice our annual average — in residents of 11 states, mainly in the Midwest but also including Texas, Georgia, Connecticut, and New Jersey. So many cases are not usually reported at once.

Health officials first noticed the current outbreak less than a month ago, when two patients from Iowa were reported to the CDC with the first laboratory-confirmed cases of Cyclospora infection. Neither had a recent history of international travel. Since then, the CDC has been collaborating with state public health officials and the Food and Drug Administration to investigate the cause of the recent cyclosporiasis.

At least 18 persons have reportedly been hospitalized in three states. Additional cases are also currently under investigation. Doctors still do not know whether all the illness came from the same source or whether the outbreaks are regional.

Like noroviruses and other gastrointestinal disease organisms, the one-cell parasite Cyclospora cayetanensis originates in human stool. This cyclospora outbreak is unlike last winter’s Sydney norovirus in that people don’t usually catch this disease from other people, but from eating fresh fruits or vegetables or drinking water contaminated with the virus. No foods have yet been implicated, but on the basis of previous outbreaks, public health authorities are investigating various types of fresh produce from different sources.

The last large outbreak in the US occurred in 1996. It resulted in at least 1,465 lab-confirmed cases in North America and was traced to contamination in raspberries from Guatemala (which had recently increased its exports), rather than California strawberries as originally thought. (Lettuce, spinach, basil, and other leafy green vegetables cause almost half of US food-related illnesses, although poultry causes the most deaths.) Special concern surrounds imports from countries with less stringent health regulations than the US.

According to the Kenyon microbe wiki, “Cyclospora is found in warm climates, mainly the tropics and subtropics. Overall the disease is quite rare, and outbreaks are relatively limited.” It was first identified in 1979.

Symptoms include watery diarrhea, stomach and gut cramping, weight loss, and anorexia. They usually begin within one week after infection and can remain for up to a month following the illness. Laboratory tests are not usually done. For most people, rest and plenty of fluids help to treat this illness.

Physicians can kill cyclospora with combined antibiotics (trimethoprim-sulfamethoxazole) like Bactrim, Septra, or Pediazole. People with sulfa allergies (3% of the population) have no effective alternatives as yet. Experimental studies suggest that drugs like ciprofloxacin may offer some benefit.

If a person is not treated, the disease can relapse. Although some patients who are infected do not show clinical signs of cyclosporiasis, see your doctor if troubling symptoms occur.
 To guard against this illness, thoroughly rinse fruits and vegetables several times. Even after washing, cyclospora may remain on produce. Washing possibly contaminated utensils and countertops carefully is also important, especially since cyclospora is resistant to disinfectants. Cooking and/or freezing usually eliminates the virus.

But all the observation, precautions, and treatments may be academic in this particular episode of food poisoning. It’s possible that as with the Guatemalan raspberries, all the food was consumed even before people started getting sick in large numbers. Most fresh foods perish quickly on their own. This outbreak started in June, and August is only a week away.

Probably, the benefit of the CDC’s investigations mostly involves the future. When epidemiologists are able to find the exact source of the parasite, producers and inspectors can take over to protect public health. In the case of Guatemala, with help from US and Canadian health officials, the national government and raspberry growers worked out a Model Plan of Excellence for handling possibly contaminated fruit.

Since 2000, imported Guatemalan raspberries have been cyclospora-free.

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