Staff Reports
the U.S. File Photo
Nearly 7,000 cases of cyclosporasis have been reported amid multiple outbreaks of the parasite.
Cyclosporasis typically spreads through contaminated food, and it’s been sickening thousands of people across the U.S.
The intestinal infection, caused by the cyclospora parasite, isn’t new, and rates typically ramp up in the summer. However, the U.S. is seeing an unusually high number of cases this season, along with mysterious clusters in several regions.
When ingested, cyclospora infects the small intestine and causes severe gastrointestinal upset. The main symptom of cyclosporasis is sudden, watery, “explosive,” diarrhea, which the U.S. Centers for Disease Control and Prevention says may persist for weeks.
On July 14, the CDC confirmed a large outbreak affecting four Midwestern states—including Michigan, which has recorded over half of all cases in the U.S.
The parasite spreads to people through contaminated food or water, and past outbreaks have been linked to fresh produce.
The U.S. Food and Drug Administration linked the outbreak back to lettuce grown by Taylor Farms in the central Mexican state of Guanajuato.
The country’s health minister, David Kershenobich, refuted the FDA’s assertion on July 21. The same day, Health and Human Services Secretary Robert F. Kennedy Jr. said in a news briefing the outbreak was “under control.”
“So far, no evidence has been found to indicate that it originated there,” Kershenobich said in a news conference, per Reuters. “However, we are taking all precautions in case that were the case.”
Kennedy and the Trump administration have faced criticism for cuts to relevant health agencies, with some critics indicating that scaled-back surveillance and limited staffing enabled not only the cyclospora spread, but other recent outbreaks like screwworm. Last year, the CDC scaled back a decades-long federal-state partnership that monitors foodborne illnesses, including those caused by cyclospora.
Authorities in the U.S. and Mexico are continuing to search for a cause behind the case clusters, a task that has proven messier than other foodborne outbreaks of the recent past.
WHAT WAS THE ‘FALSE POSITIVE’ ALL ABOUT?
The FDA retracted a positive Cyclospora parasite test on a Taylor Farms lettuce sample July 19, calling it a false positive. However, officials emphasize that overwhelming epidemiological data still links the supplier’s shredded iceberg lettuce to the multistate cyclosporiasis outbreak.
In a July 20 clarification, the agency said its false positive doesn’t change its prior conclusion that the outbreak is linked to shredded iceberg lettuce from central Mexico supplied by Taylor Farms, which was also served at some Taco Bell locations. The agency is still advising Americans not to eat recalled iceberg lettuce.
“FDA’s traceback investigation and outbreak data continue to converge on shredded iceberg lettuce from Taylor Farms locations in central Mexico,” it said in a statement. “FDA will continue to work with federal and state partners to investigate this multistate outbreak and ensure products implicated in this outbreak have been removed from the market.”
In foodborne outbreak investigations, a false positive can happen when an initial screening signal isn’t reproduced during confirmation testing.
Cyclospora tests are prone to false positives because the process for conducting them can sometimes make it look like there’s a parasite in the sample when there’s not, Donald Schaffner, chair of food science at Rutgers University, told CNBC. He said the FDA’s own protocol recommends conducting another test to confirm the result.
