National intestinal parasite outbreak hasn’t reached SLO County. How to stay safe
As an outbreak of intestinal parasites rolls across the United States, residents of San Luis Obispo County appear to have been spared — but that’s no guarantee of the future.
Over the course of this month, reports of cases of cyclosporiasis have spread like wildfire, with more than 30 states reporting cases of the parasite as of Tuesday, according to Johns Hopkins Medicine.
Cyclosporiasis is the intestinal illness caused by the Cyclospora cayetanensis parasite, which can only be seen under a microscope and spreads quickly by ingesting food or drink that’s come into contact with infected feces — in this case, mostly raspberries, basil, cilantro, snow peas and mesclun lettuce, according to the U.S. Food and Drug Administration.
Worst of all, the distinctive symptoms of cyclosporiasis — watery, acute cases of diarrhea — can persist for weeks or months if untreated, according to Johns Hopkins.
According to the Centers for Disease Control and Prevention, since May 1, the agency has confirmed 1,645 lab-confirmed cases of domestically acquired Cyclospora, and is aware of more than 5,100 additional reports that require further analysis to confirm they meet the case definition.
The 34 states that have seen the highest occurrence of the illness are largely concentrated in the Midwest and eastern United States, while states like California have largely been spared the worst of the outbreak, San Luis Obispo County Public Health interim health officer Dr. Rick Rosen said.
“In California, we haven’t seen anything sort of out of the norm, both in the state and locally,” Dr. Rosen said. “In both cases we’ve seen sporadic cases here and there, and that’s normal for us, and that continues to be the case.”
No outbreak-related cases reported in SLO County
Dr. Rosen said the California Department of Public Health has reported a lower-than-normal number of cyclosporiasis cases this year, bucking the national trend.
According to the Department of Public Health, from January to June 2026, California has reported 41 provisional cases of cyclosporiasis, compared to 80 cases during the same period in 2025, while the annual average number of cases from 2015 to 2025 is 106 cases.
Still, Dr. Rosen advised common sense caution when handling or eating fresh produce.
Fruits and vegetables should be washed under running water with the hands or a brush, and should immediately be stored in the refrigerator, he said.
Heating food to at least 158 degrees Fahrenheit can also kill cyclospora, according to the state of Michigan’s Department of Health and Human Services, which is one of four states currently experiencing the highest number of cases.
“I certainly don’t want to tell folks that you have to stop eating uncooked fruits and vegetables, because that like for me that would mean no lunch,” Dr. Rosen said. “If you do the common sense things — and especially in our case, where there hasn’t been an outbreak — that sort of that reduces the risk for cyclosporiasis and other illnesses.”
In 2025, the Trump administration made surveillance of cyclospora and several other foodborne pathogens optional in FoodNet, which is the CDC, U.S. Food and Drug Administration, Department of Agriculture and state health departments’ collaborative food safety program.
However, Dr. Rosen didn’t indicate that this reduction in food surveillance standards can be directly linked to the current outbreak.
“The mechanism for a response is still the same,” Dr. Rosen said. “The outbreak is identified, epidemiologists respond to the outbreak, do an investigation, try to identify the source that is the culprit and that’s still happening.”
Exercise caution where possible
While the risk of contracting cyclosporiasis locally is low, anyone who suspects they have come into contact the illness should speak to their doctor or urgent care, Dr. Rosen said.
While more common bouts of diarrhea typically last 48-72 hours, cyclosporiasis can last weeks to months if untreated, and can look and feel like more common diarrheal illness, Dr. Rosen said.
Cyclosporiasis can be easily treated using prescription antibiotics, but a doctor would require a stool sample to identify the illness, Dr. Rosen said.
Anyone who tests positive for cyclosporiasis should expect to receive a call from the county Department of Public Health in the days following the test, in order to trace the illness to its source locally, Dr. Rosen said.
“There are probably a lot more cases than we know of, because it’s dependent on people going in to see their doctor, going into urgent care, and ... submitting a stool specimen to identify cyclospora,” Dr. Rosen said. “That’s really the first step.”
