A parasitic infection that causes miserable bouts of watery, “explosive” diarrhea is spiking across the United States. Several states are seeing cases at rates that appear to be higher than this time last year. Meanwhile, health authorities are scrambling to identify the source driving the surge.
As of July 14, about 5,000 cases of cyclosporiasis have been reported by at least 31 states, according to NBC News’ latest tally based on information from state health departments.
At least 86 people have been hospitalized with the parasitic illness so far, per the U.S. Centers of Disease Control and Prevention.
“Cases are simply exploding across the country,” NBC medical contributor and ER physician Dr. John Torres said on TODAY in a July 14 segment.
Michigan, New York, Ohio and North Carolina are among the states hit hardest by the parasitic illness.
Cyclosporasis rates normally increase in the U.S. during the warmer months, according to the the CDC. But the recent surge has sparked some concern.
“When we started seeing cases of persistent diarrhea showing up, we knew there’s something going on,” Dr. Brian Kaminski, vice president of medical affairs at ProMedica Health System, which sees patients in Michigan and Ohio, told NBC News.
The infection is caused by the Cyclospora cayetanensis parasite, which spreads through food and water contaminated with feces from an infected person, also known as the fecal-oral route. Person-to-person spread is highly unlikely, per the CDC.
In the U.S., cyclosporiasis outbreaks are commonly linked to fresh produce. When ingested, cyclospora infects the small intestine and leads to watery, explosive diarrhea.
Cyclosporiasis is usually not life-threatening, per the CDC. However, it is extremely unpleasant, and the episodes of severe diarrhea can last for weeks — which can put a real damper on vacation plans.
So far, it’s unclear if the outbreaks in multiple states are connected, the CDC said, but investigations are ongoing.
Where Are Cyclosporiasis Cases Rising?
Nationally, cyclospora infections have been ramping up since spring.
The U.S. has seen about 5,010 cases of cyclosporiasis as of July 14, according to NBC News’ latest tally.
Additionally, the CDC confirmed that 843 cases of cyclosporiasis were reported in 31 U.S. states from May 1 to July 9. (This data does not include all the latest case counts reported by state health departments.)
In a July 10 update, the CDC said “it is aware of more than 1,500 cases that require further analysis to confirm the illness as domestically-acquired cyclosporiasis.”
The true number of people infected with cyclospora in the U.S. is likely higher than the numbers being reported because “some people recover without medical care and are not tested for cyclospora,” the CDC said.
Some 35 states’ health departments responded to requests from TODAY.com and NBC News about whether there have been recent cyclosporiasis spikes.
Michigan
In Michigan, health officials are seeing an unprecedented “sudden and large” increase in infections with the diarrhea-causing parasite, TODAY.com reported previously.
As of July 14, Michigan has reported 3,309 cases of cyclosporiasis since the end of June, according to the Michigan Department of Health and Human Services. At least 44 of those sickened required hospitalization.
The total number of reported cases is over 65 times higher than the annual average for the state, which records about 40-50 cases a year, a spokesperson for MDHHS said.
Dr. Natasha Bagdasarian, chief medical executive for the state of Michigan, told NBC News that the recent, sharp increase in cases is “highly unusual.”
Ohio
As of July 10, the Ohio Department of Health has reported at least 364 cyclosporiasis cases in 2026 — of those, at least 171 occurred since late June, a spokesperson for the Ohio Department of Health said.
The recent surge in cases in Ohio and Michigan may be part of an “epidemic cluster,” Kaminski said.
New York
New York state has recorded approximately 394 cyclosporiasis cases since May 1, a spokesperson for the state health department told TODAY.com in a July 9 statement. Typically, the state records 500-700 cases a year.
“New York’s current case counts do not represent a major deviation from the norm this time of year,” the spokesperson said.
North Carolina
As of July 13, North Carolina has reported 240 cyclospora infections since May, according to a statement from the North Carolina Department of Health to NBC News.
Illinois
The Illinois Department of Health told NBC News that the state has seen 216 cases as of July 14, a “higher than average” number, with no single potential cause identified.
Colorado
Colorado has reported 90 cases of cyclosporiasis so far, a public health spokesperson for the state told NBC News.
Indiana
Some 72 cases have been reported in Indiana since May 1, a state spokesperson told NBC news.
Texas
Texas has reported 48 cases between May 1 and July 6, resulting in five hospitalizations and no deaths. No common source has yet been identified, per a statement from the Texas Department of Health.
Is There a Cyclosporiasis Outbreak in the U.S.?
The CDC and U.S. Food and Drug Administration are currently investigating outbreaks of cyclosporiasis in multiple states. It’s unclear if these outbreaks and clusters are connected.
A CDC spokesperson previously told NBC News that it “has no evidence of a single, multistate Cyclospora outbreak linking cases happening right now and being reported in the press.”
It’s not out of the norm to see cyclospora infections increase around this time of year. In the U.S., cyclosporiasis season usually lasts from May to August, per the CDC.
However, it appears there may already be more cases reported this year than last year. NBC News’ tally shows over 5,000 reported or confirmed cases nationwide for 2026. Dianna Blau, acting chief of the CDC’s Parasitic Disease Branch, told NBC News that the U.S. reported about 2,700 cases in all of 2025.
“So far this year, multiple states have reported an increase in cases in the last two weeks compared to the same period in 2025,” the CDC said in a July 10 update.
The massive increase in cyclosporiasis in Michigan and other states has prompted investigations into a common source.
On July 13, Michigan health officials announced that early results point to “lettuce or salad greens” as a potential source of the outbreak, but that it could not rule out other foods. “No specific type of produce, grower or supplier has been identified,” the MDHSS said.
In the past, cyclosporiasis outbreaks have been linked to salad greens, raspberries, basil, cilantro, green onions and snow peas.
Cyclosporiasis Symptoms
The most common symptom of cyclosporiasis is sudden, watery diarrhea. According to the CDC, these bowel movements are often frequent and “explosive.”
In addition to diarrhea, people may experience severe stomach cramps, bloating, vomiting, nausea, loss of appetite, and fatigue, per the Cleveland Clinic.
These can last for several days to several weeks or longer. The bouts of diarrhea may occur in cycles and “relapse” after you seem to feel better, the CDC says.
It can take up to 14 days after ingesting food or water contaminated with cyclospora for symptoms to start.
Compared to norovirus, another common illness that causes GI upset, cyclosporiasis typically takes longer to show symptoms and is more likely to cause diarrhea and cramping than vomiting, Bagdasarian said.
Most healthy people will recover from cyclosporiasis on their own, per the CDC, but the infection can be treated with a combination antibiotic. People with weak immune systems are at higher risk for recurring symptoms and may require more extensive treatment.
If you develop signs of cyclosporiasis or sudden and severe gastrointestinal illness, contact your health care provider.
How to Prevent Cyclosporiasis
The only way to prevent cyclosporiasis is to avoid consuming food or water that may be contaminated with feces.
Food safety experts told TODAY.com that at this stage, there is no reason for Americans to stop eating fresh produce due to the rise in cyclosporiasis.
“Almost all servings of fresh fruits and vegetables that you can buy on the market today are not linked to this outbreak,” Donald Schaffner, Ph.D., a professor of food microbiology in the Department of Food Science at Rutgers University, tells TODAY.com.
However, people can take extra steps in the kitchen.
Cooking food to 158 degrees Fahrenheit is the only way to destroy cyclospora. Freezing can inactivate the parasite, but it’s not a guarantee.
Washing fresh produce can help lower the risk of cyclospora and other foodborne pathogens. “It’s not going to completely protect you, but it’s certainly going to minimize the amount of parasites that might be in there,” said Torres.
Here are a few more tips to prevent cyclospora from state health departments:
- Wash your hands with soap and water before and after handling raw produce.
- Thoroughly wash all fresh produce under clean, running water. Do not use soap.
- Scrub fruits and vegetables with a produce brush.
- Remove the outer layers, leaves and peel of produce when possible (such as with lettuce heads).
- Separate fresh basil and cilantro leaves and run them under running water before eating.
- Cut away any damaged areas on fresh produce before eating.
- Refrigerate fruits and vegetables (cooked or fresh) within two hours of preparing it.
Michigan health officials have also shared “lettuce-specific safety measures” for people living in affected counties in the state.
