Cyclosporiasis: Linked to produce, leading to diarrhea

Cyclosporiasis is an illness caused by a parasite called Cyclospora cayetanensis, which infects the digestive system. People become infected after consuming food or water contaminated with the parasite. It is not usually spread directly from person to person.

"It's summertime," says Dr. Smith, “which tends to be a nice environment for the organisms to flourish, particularly in watershed areas.”

The CDC says cases reported this year in many states are significantly higher than those reported during the same period in 2025 and are quickly increasing nationwide. Federal, state and local public health officials are working to determine the sources of illness, but investigations are ongoing.

"Produce can come from all over the world," says Dr. Smith. “So, I don't think it's a safe thing to assume that that's not going to reach us here in San Diego.”

However, according to the California Department of Public Health, California is not among the states currently experiencing an outbreak of cyclosporiasis. To-date, California has seen fewer cases of cyclosporiasis in 2026 than in 2025. And the department calls local cases “well within expected ranges for California.”

Symptoms of cyclosporiasis can appear anywhere from two to 14 days after exposure. According to the CDC, the most common symptom is watery diarrhea.

Other symptoms may include:

• Loss of appetite

• Weight loss

• Bloating

• Stomach cramps

• Nausea

• Fatigue

• Vomiting

• Low-grade fever

Without treatment, symptoms can last for weeks and may come and go, leading to dehydration. People who experience severe diarrhea, signs of dehydration or prolonged symptoms should talk with their doctor.

"If profound dehydration ensues, it can lead to admission to one of our local hospitals," says Dr. Smith.

Anyone can become sick due to cyclosporiasis, but the effects may be more serious for people who become dehydrated quickly or who have weakened immune systems. Young children, pregnant women and older adults are at increased risk.

Diagnosis of cyclosporiasis typically requires a test that specifically looks for the parasite in a person’s stool (poop). To treat it, the CDC recommends an antibiotic combination called trimethoprim-sulfamethoxazole (TMP-SMX). Although cyclosporiasis may improve without medical care, early treatment can shorten the duration of illness and help prevent symptoms from lingering or coming back.

Not always. "A lot of people will think, 'Oh, well, I'll just wash my produce super well,'" says Dr. Smith. "But this time, that might not be so simple."

The parasite can be difficult to remove from fresh fruits and vegetables. So, routine rinsing, although still recommended, may not fully eliminate the risk of infection.

What’s more, the CDC notes that there is no guaranteed way for shoppers to identify contaminated produce. In the past, raspberries, basil, cilantro, green onions, snow peas, lettuce, mesclun and bagged salad mixes have been common sources of contamination.

Although public health officials have not yet identified the source of the recent cases, there are several precautions people can take to decrease the risk of foodborne illness.

The CDC recommends:

• Washing hands with soap and water before and after handling or preparing raw fruits and vegetables.

• Thoroughly washing produce under running water even if it is labeled as pre-washed or if you plan to peel it

• Scrubbing firm fruits and vegetables, such as melons and cucumbers, with a clean produce brush

• Washing and sanitizing cutting boards, surfaces and utensils used to prepare, serve or store fresh produce

• Cutting away damaged or bruised areas on fruits and vegetables before preparing and eating

• Refrigerating cut, peeled or cooked fruits and vegetables as soon as possible (within two hours)

Additionally, because health officials in Michigan are considering whether lettuce or salad greens are the cause of their recent outbreak, they recommend buying whole heads of lettuce rather than prewashed, bagged lettuce or salad mixes. Throw away the outer two to three layers of leaves and wash the inner leaves under running water.

According to Dr. Smith, cooking foods thoroughly offers additional protection. "If you boil produce at a higher temperature or cookit to 158° F or higher, then you can be sure that the organism is not going to cause problems," he says.