CDC: Cyclosporiasis outbreak grows to 4,100 cases, 7,500 more unconfirmed
Signage outside the Center for Disease Control (CDC) headquarters in Atlanta, Georgia, US, on Friday, Dec. 5, 2025. Photographer: Megan Varner/Bloomberg via Getty Images
U.S. health officials say they now have 4,173 laboratory-confirmed cases of cyclosporiasis that have been reported since May 1, as investigators continue a multistate investigation into an outbreak linked to iceberg lettuce distributed by Taylor Farms.
The Center for Disease Control and Prevention said they are also aware of more than 7,400 additional illnesses that have not yet been laboratory confirmed, with many of those reports coming from Michigan and Ohio.
The backstory:
Cyclosporiasis is a gastrointestinal disease caused by the microscopic parasite cyclospora. Symptoms can appear two to 14 days after exposure and may include frequent watery diarrhea, loss of appetite, cramping, nausea and a fever.
The FDA initially said a sample of the Taylor Farms’ lettuce did test positive for the parasite after the supplier pulled all iceberg lettuce from central Mexico heading to the United States. However, they later said samples of lettuce that were collected should be considered a false positive.
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By the numbers:
Officials expect case counts to rise due to reporting delays and say the true number of infections is likely higher. The CDC said 308 people with confirmed domestically acquired infections have been hospitalized, with no deaths reported. Cases span 41 states, and patients range in age from 2 to 95, with a median age of 44.
Big picture view:
Unlike pathogens such as salmonella or E. coli, which can be sequenced and matched through national databases, cyclospora cannot be traced using those same methods. Scientists have to take genetic material from the organism and make synthetic copies of the DNA, which could lead to a false positive, as we saw in the case with Taylor Farms.
The CDC urged doctors to start testing for cyclospora to make sure people are treated properly. With the publicity that has been generated by the recent outbreak of cyclospora, experts say more people are likely seeking out testing.
RELATED: Taylor Farms recall: States where lettuce pulled over Cyclospora fears
Monitoring and investigating cyclosporiasis cases
The backstory:
The CDC and federal health authorities monitor laboratory-confirmed cases of cyclosporiasis throughout the year to detect outbreaks. Regular monitoring helps in identifying and investigating outbreaks.
The CDC works with local, state and federal partners to combine patient interviews, food tracebacks and lab testing to find the source of multistate outbreaks. Many foods have multiple produce ingredients, like salads or salsa, making determination on a single food item difficult.
The Source: This story was written with information provided by the Center for Disease Control and Reuters. This story was reported from Orlando.