Diarrhea-causing disease hits double average cases in California

Reported cases of the parasitic disease cyclosporiasis are on the rise in California, with a total of 215 cases in 2026 so far — more than double the yearly average of 106.

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The increase in cases comes amid a massive nationwide outbreak of cyclosporiasis, which causes watery and explosive diarrhea along with nausea and weight loss. Currently, the U.S. Centers for Disease Control and Prevention have reported 6,358 confirmed cases of the parasitic disease across 15 states, believed to be linked to iceberg lettuce sold by Taylor Farms.

In addition to those cases, multiple smaller cyclospora outbreaks without a known source have been reported by the U.S. Food and Drug Administration. In total, there are 10,468 laboratory-verified cyclospora cases in the U.S., along with another 12,255 cases under investigation.

However, despite the rise in cyclospora cases in California and the nation, the state’s public health department said there’s no sign of a major outbreak in the state.

Since May 1, when cyclospora cases began to rise nationwide, California has reported 201 cases. Of these cases, the vast majority — 172 — were acquired while the individual was abroad, which is traditionally how most U.S. residents get sick. 

Of the 43 domestically acquired cases, 15 involved people who left the state but stayed within the U.S. Just two individual cases are believed to be linked to the outbreak that’s connected to tainted lettuce. They were sickened after traveling outside California and eating items at a Taco Bell. 

In a statement to SFGATE, Beth Deines, a spokesperson for the California Department of Public Health, said there are currently “no known” outbreaks of cyclosporiasis in the state but noted that cases are elevated. The CDPH is currently investigating the increase and thinks it may be the result of multiple factors, Deines continued. These include people with the condition seeking out treatment and testing, better public health surveillance of the disease due to media coverage, or the fact that more people are traveling and getting sick while they’re outside the state. 

Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center, said the additional cases may actually be a sign of the public health department’s effective messaging.

“There are probably cases year in and year out that go undiagnosed and unfortunately untreated as a consequence,” he said. “As you raise everyone’s awareness, they’re looking harder. If you turn over more rocks, you’ll find more worms.”

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Regarding the newly reported outbreaks without a known source, Schaffner said there may be cases caused by cross-contamination with affected produce.

“You likely have other subsidiary outbreaks that are also related to the similar kind of food … often fresh produce that’s mixed together,” he said.

Dr. Monica Gandhi, an infectious disease expert at UC San Francisco, said the news that cyclospora outbreaks are coming from an unknown source is concerning.

“We still have really, really high numbers of cyclospora cases, beyond that outbreak, that no one knows where they’re coming from,” she told SFGATE. “That gives me concern that there are other foods that are contaminated, that we just haven’t gotten to the source of what’s the link between all these increased cases.” 

Both Gandhi and Schaffner said they worry about the federal government’s ability to respond to these types of outbreaks after the CDC had major cutbacks last year, losing about a quarter of its workforce.

“It isn’t a state-specific problem,” Gandhi said. “If there is a farm that produces food that goes across the country, then we wouldn’t be able to understand those patterns.”

Gandhi said the CDPH “alone cannot detect those sort of patterns. That’s why we need a national public health workforce.”