Social media has been awash with “produce paranoia,” as videos depict people emptying their refrigerators, vowing to avoid salads, and questioning the safety of herbs like cilantro.
This frenzied reaction follows a sharp rise in cases of a diarrhea-causing parasite spreading across the United States, while health officials work to pinpoint which produce items are driving the outbreak.
The illness, cyclosporiasis, stems from the cyclospora parasite—a foodborne pathogen notoriously difficult to trace that has historically been linked to fresh produce like berries and lettuce. For weeks, investigators could not identify a specific food, brand, grower, or supplier, fueling public anxiety and a wave of dark humor online.
Late Thursday, the CDC announced an investigation into a potential link to shredded iceberg lettuce served at Taco Bell restaurants in Indiana, Kentucky, Michigan, Ohio, and West Virginia. The agency advised consumers in those states to avoid the shredded lettuce from those locations. Taco Bell is reportedly removing the implicated produce and coordinating with its supplier to assess whether other locations received the contaminated product.
As of earlier this week, the CDC had recorded 1,645 lab-confirmed domestic cases of cyclosporiasis and was reviewing an additional 5,100 reports. Infections have surfaced in 34 states, with Michigan experiencing a particularly high concentration.
Misinformation often spreads as quickly as the illness itself during a health scare. To separate fact from fiction, we consulted infectious disease experts.
“I wouldn’t necessarily suggest that people avoid produce,” said Dr. John Openshaw, an infectious disease physician and medical epidemiologist at Stanford University. “Even though the number of people affected in the current outbreak appears large, the overall risk to most individuals remains very low.”
What is cyclosporiasis?
Cyclosporiasis is caused by Cyclospora cayetanensis, a microscopic parasite transmitted via fecal matter that infects the small intestine. Infectious disease experts at Johns Hopkins note that ingesting just a few microscopic oocysts can trigger infection.
In the U.S., past cyclospora outbreaks have frequently been traced to fresh produce such as bagged salad mixes, cilantro, basil, raspberries, snow peas, and green onions. Any contaminated food consumed raw can potentially transmit the parasite.
Unlike norovirus, cyclosporiasis rarely spreads directly between people. Once excreted, the parasite typically requires one to two weeks in the environment to become infectious.
Stomach cramps are a common sign of cyclosporiasis, an infection caused by the cyclospora parasite.
What are the symptoms of cyclosporiasis?
The hallmark symptom is profuse, watery diarrhea that the CDC describes as occasionally “explosive.” Additional symptoms may include stomach cramps, nausea, loss of appetite, bloating, gas, fatigue, vomiting, and low-grade fever.
While not typically life-threatening like listeria or E. coli, cyclosporiasis poses a significant dehydration risk, especially during summer. “Anyone struggling to stay hydrated should consult a physician,” Openshaw advised.
Symptoms usually emerge about a week post-exposure, though the incubation period can range from two days to over two weeks. Dr. Timothy Henrich, a professor of medicine at UCSF, noted that patients often experience a relapsing-remitting course over weeks or months, while some remain asymptomatic.
Given the fluctuating nature of symptoms, testing for cyclosporiasis and discussing treatment with a healthcare provider is crucial. The standard therapy is generally well-tolerated and “may reduce the chances of further local fecal-oral spread,” Henrich added.
How high is the risk?
Although cases have been reported nationwide, the outbreak is heavily concentrated in a cluster of Midwestern states. Jessica Steier, a public health scientist and CEO of Unbiased Science, said the risk remains low outside those areas, though she advised that “pregnant or immunocompromised individuals might consider erring on the side of caution.”
The CDC reports that roughly 9% of infected individuals require hospitalization, with seniors, young children, and those with weakened immune systems facing a higher risk of severe complications. No deaths have been linked to the outbreak as of Tuesday.
Health officials says it’s best to avoid bagged greens or precut mixes to stay safe during the current cyclospora outbreak.
How can you reduce your risk?
As of Tuesday, no nationwide recall or avoidance advisory for lettuce had been issued. However, Michigan health officials have released specific guidance for the current investigation, recommending that consumers purchase whole heads of lettuce rather than bagged or pre-mixed varieties, discard the outer three layers of leaves, and cook leafy greens when feasible.
While washing produce may reduce exposure to cyclospora and other contaminants, it cannot guarantee complete removal of the parasite.
“Washing produce does not meaningfully decrease the risk of cyclospora; heat remains the gold standard for risk reduction,” Steier said. Cooking vegetables to an internal temperature of at least 158°F (70°C) is the only reliable method to kill the parasite.
Experts also caution against using soap, bleach, or household disinfectants on produce. Fruits and vegetables can absorb these chemicals, potentially causing illness, and the CDC states that routine chemical disinfection is unlikely to eliminate cyclospora.
Similarly, consumer devices such as UV produce washers, ultrasonic cleaners, or ozone generators have not been proven effective against cyclospora. Steier confirmed that none of these methods have sufficient real-world evidence to support their use for parasite eradication.
What should you do if you have symptoms?
Experts recommend contacting a healthcare provider if you experience persistent watery diarrhea, particularly if it is severe, lasts more than a week, or recurs after improvement. Maintaining fluid intake is critical to prevent dehydration.
Diagnosis requires specialized laboratory testing, as cyclospora is not detected by standard stool panels. The CDC notes that multiple samples may be necessary because the parasite can be difficult to identify.
The first-line treatment is the antibiotic combination trimethoprim-sulfamethoxazole (commonly known as Bactrim or Septra). Patients with sulfa allergies should consult their provider for alternative therapies.
The CDC hasn’t found a single source linking the outbreak.
Why is it so hard to identify the source of an outbreak?
Pinpointing the source of a parasitic outbreak often takes weeks or longer, as investigators must compare dietary histories of affected individuals and trace implicated foods through complex supply chains. For cyclospora, this process is especially challenging because symptoms typically appear days to weeks after exposure.
Compounding the challenge, public health agencies have endured staffing cuts and funding reductions in recent years, hampering rapid outbreak detection and public notification. A recent study found that states with greater CDC support reported more outbreaks, suggesting that robust federal funding enhances detection and response capabilities.
“Tracing an outbreak of this nature requires trained personnel and adequate resources; any reduction in those capacities impedes efforts to link an outbreak to a specific food item and determine how a pathogen like cyclospora entered the food supply,” Openshaw said.
