Cyclospora cases are rising well above normal levels across multiple US states this summer, with investigators tracking clusters linked to restaurants, grocery chains, and catered events. Here is what you need to know about the parasite, how it spreads, what it feels like, and what to do if you think you have it.

What Is Cyclospora?

Cyclosporiasis is an intestinal infection caused by the single-celled parasite Cyclospora cayetanensis, which spreads through human feces. People typically get it by eating or drinking contaminated food or water — most often raw produce or water sources such as lakes, swimming pools, splash pads, and water parks.

The foods most frequently associated with US cyclospora outbreaks since the mid-1990s include raspberries, basil, salad mixes, cilantro, berry and fruit mixes, lettuce, and snap peas. Produce with bumpy or textured surfaces — like raspberries — is especially difficult to clean thoroughly and has been linked to the most outbreaks.

Because cyclospora spores need time to mature outside the body before becoming infectious, the parasite does not typically spread directly from person to person. Transmission happens more indirectly, through contaminated food or water.

How Bad Is the Current Outbreak?

Federal health officials say they are seeing a higher-than-expected number of cyclosporiasis cases across several states. Michigan — which typically logs around 50 cases per year — has now recorded 681 cases since June 22 alone, pointing to a concentrated outbreak with a common source. Ohio has reported 177 cases so far this year, with 171 arriving in June. New York state has logged 112 cases outside New York City this year, with 107 since May 1.

The CDC is investigating clusters in Illinois, New York City, New York State, Pennsylvania, and Texas, with traceback investigations targeting white and green onions, cucumbers, and cilantro as potential sources. At least eight additional clusters have been identified in Alabama, Kentucky, Michigan, Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia. The CDC says there is no evidence yet of a single multistate outbreak linking all cases.

Why Is Cyclospora So Hard to Trace?

Investigators face a major challenge: cyclospora is far harder to track through genetic testing than common foodborne pathogens like salmonella or E. coli. Because the parasite reproduces sexually — swapping genetic material between male and female forms — its DNA changes significantly from one generation to the next, making standard gene-matching techniques less reliable.

“Cyclospora is a weird one,” said Dr. Max Teplitski, former head of the USDA’s Division of Food Safety. Scientists at the CDC have developed genotyping methods that can roughly group cases into strains, but the precision falls well short of what is possible with bacterial pathogens. As a result, outbreak investigations still depend heavily on detailed interviews with sick individuals, grocery receipts, and credit card data to reconstruct what people ate and when — a slow and painstaking process.

What Are the Symptoms?

Cyclospora symptoms are distinct from most common stomach bugs. The hallmark is frequent, very watery diarrhea — more than three times a day — accompanied by bloating, cramping, loss of appetite, and a persistent feeling of fullness. Fever is possible but uncommon.

“It’s sort of like you just ate Thanksgiving dinner, but every day,” said Dr. Rebecca Schein, an infectious disease expert at Michigan State University Health Care. The illness can persist for weeks in people with normal immune systems — sometimes up to six weeks — with symptoms that may come and go. In people with compromised immune systems, symptoms will not resolve without treatment.

Symptoms typically begin one to two weeks after consuming contaminated food or water.

How Is It Diagnosed?

Cyclospora is not included on standard multiplex stool tests that doctors routinely order for stomach illnesses. A specific test is required — one that uses a special stain to make the parasite’s eggs appear bright pink or orange under a microscope. Because the eggs shed inconsistently, Texas health officials have recommended testing as many as three stool samples spaced 24 hours apart to confirm a diagnosis.

If you have had diarrhea lasting more than three to five days — or more than two days if you live near a known outbreak — doctors recommend getting tested specifically for cyclospora.

How Is It Treated?

Once diagnosed, treatment is straightforward. Cyclospora is treated with a combination antibiotic called trimethoprim-sulfa, sold under the brand names Bactrim and Septra. A standard course runs seven to ten days, though people with weakened immune systems may require longer treatment. The antibiotic works by blocking the parasite’s ability to use the vitamin folate to generate energy.

Treatment is recommended for all confirmed cases both to relieve prolonged discomfort and to reduce environmental spread.

Does Washing Produce Help?

Research suggests that washing helps but does not fully eliminate the risk. A Norwegian study contaminated raspberries and blueberries with cyclospora and tested three washing methods: plain tap water, a salad spinner, and a vinegar-water solution. All three removed most but not all of the parasite’s eggs. Vinegar water was slightly more effective than plain water alone, but none of the methods achieved complete removal. Smooth berries like blueberries were easier to clean than the textured surface of raspberries.

The FDA recommends the following produce handling practices to reduce risk from cyclospora and other foodborne pathogens: wash hands for 20 seconds with soap and warm water before and after handling produce; rinse produce before peeling to prevent surface contamination from transferring to the flesh; gently rub produce under running water; use a clean vegetable brush on firm produce like cucumbers and melons; dry produce with a clean cloth or paper towel; and remove the outermost leaves of lettuce or cabbage before using.

Soap and produce washes are not necessary, the FDA says — plain running water is sufficient. Thorough washing is always good practice, even if it cannot guarantee complete protection against cyclospora.

Author: Staff Writer | Edited for WTFwire.com | SOURCE: CNN News