Cyclospora, Salmonella: How to Tell Symptoms Apart

0 Share Newsweek is a Trust Project member See more of our trusted coverage when you search. Prefer Newsweek on Google to see more of our trusted coverage when you search. Americans are tracking two separate foodborne illness outbreaks linked to staple grocery items: a record-setting cyclospora outbreak associated with recalled iceberg lettuce and a multistate salmonella outbreak tied to recalled shell eggs.

While both illnesses can cause gastrointestinal distress, health experts say there are important differences in how they spread, when symptoms appear and how long people can remain sick. The cyclospora outbreak has resulted in 4,173 laboratory-confirmed cases across 41 states as of July 24, according to the Centers for Disease Control and Prevention ( CDC ), while an ongoing salmonella outbreak linked to recalled shell eggs has sickened 98 people across 17 states.

The two illnesses can initially seem similar because both commonly cause diarrhea, stomach cramps and nausea. However, there are some key differences.

"The most reliable way to tell them apart is timing," Dr. Tyler Evans, founder and CEO of Wellness Equity Alliance, told Newsweek . "Salmonella tends to come on fast, often within a day of a contaminated meal, with fever and cramping and sometimes bloody diarrhea. Cyclospora is a slow burn. Symptoms usually appear about a week after exposure, and the diarrhea is watery rather than bloody, with a lot of fatigue, loss of appetite, and weight loss."

As for symptoms, cyclospora infections are often marked by:

Symptoms can persist for weeks or even months without treatment. Vomiting is a less common symptom with cyclospora, as is a fever, headache and body aches.

More severe cases of salmonellosis may include:

Diarrhea accompanied by fever and abdominal cramps, usually resolving within several days to a week, although severe cases may require hospitalization.

Although symptoms between the two can overlap, the biggest difference is the length of time someone feels sick. For salmonella, most cases resolve after a week without treatment, whereas cyclospora can persist for weeks or even months without treatment.

"There is one clue that points strongly to the parasite. Cyclospora relapses. People feel better, then it comes back," Evans said. "If a stomach illness keeps returning over a couple of weeks, that is not typical salmonella, and it is worth asking specifically about Cyclospora."

The states most heavily affected by the cyclospora outbreak appear to be Michigan and Ohio, which have reported some of the largest case totals. Federal investigators have linked one major cluster involving 1,947 confirmed illnesses in nine states—Illinois, Indiana, Kansas, Kentucky, Michigan, Ohio, Oklahoma, Pennsylvania and West Virginia—to shredded iceberg lettuce supplied by Taylor Farms de Mexico and served at Taco Bell locations. However, a spokesperson with Taylor Farms told Newsweek that there have been no confirmed positive sample results for product testing for cyclospora as of July 24.

For the salmonella outbreak, Texas has reported the largest number of illnesses. The CDC says contaminated shell eggs produced by Midwest Poultry Services in Texas are the likely source. Cases have been identified in 17 states, including Texas, Louisiana, Arizona, South Carolina and others.

Cyclospora infections can sometimes improve without treatment, but health officials caution that the illness often lingers significantly longer than many other foodborne diseases. The parasite , Cyclospora cayetanensis , causes an intestinal infection known as cyclosporiasis . Symptoms may come and go, creating a cycle in which patients appear to recover before becoming ill again.

Doctors frequently prescribe the antibiotic trimethoprim-sulfamethoxazole, commonly sold under the brand name Bactrim, to shorten the illness and reduce complications. Without treatment, some people report symptoms lasting for weeks or months.

Another difference between cyclospora and salmonella is the incubation period.

Salmonella symptoms usually develop within six hours to six days after exposure. Cyclospora can take considerably longer. The CDC says people typically become ill about one week after consuming contaminated food or water, although symptoms can emerge anywhere from roughly two days to two weeks later.

That delay can make cyclospora outbreaks difficult to investigate because many patients struggle to remember exactly what they ate days earlier. It can also slow efforts to trace contaminated products through the food supply chain.

As of late July, federal investigators have not identified BrightFarms as a source of any cyclospora outbreak.

"Our leafy greens are grown in controlled greenhouse environments with rigorous food safety standards," BrightFarms said in a frequently asked questions webpage. "Additionally, our greenhouse system helps reduce exposure to outside environmental factors like runoff water and other potential sources of contamination. We're committed to providing safe, high-quality greens for our consumers."

Other leafy green companies, such as Gotham Greens and Little Leaf Farms, have also said their products are not affected because of the way they are grown.

The FDA and CDC have instead focused much of their investigation on shredded iceberg lettuce linked to Taylor Farms de Mexico. Epidemiologic and trace-back evidence continue to point toward that supply chain as the source of the large nine-state outbreak. Taylor Farms voluntarily recalled affected iceberg lettuce products on July 17 while investigators continue their work.

The CDC says the 2026 cyclospora season officially began on May 1, which is when surveillance counts started increasing. The agency notes that cyclospora cases typically rise during the warmer months between May and August.

For the nine-state lettuce-linked outbreak, illness onset dates currently stretch from June 22 through at least July 20. Investigators continue t...

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