Diarrhea Parasite Outbreak: 7 Things To Know And What To Do In Rhode Island

Health officials still don’t know the source of an outbreak of cyclosporiasis, a parasitic illness that can cause relentless watery diarrhea that has sickened about 1,700 people in more than two dozen states, including Rhode Island, since mid-May.

The Centers for Disease Control and Prevention has confirmed outbreak cases in 17 states, but state health departments have reported illnesses in more than two dozen states. The broader total includes cases that may not meet the CDC’s definition for inclusion in the multistate outbreak.

At least 145 cases have been reported to the CDC, with 20 requiring hospitalization, while The Associated Press said its reporting showed about 1,700 people in 29 states have been sickened. Michigan is hardest hit, with more than 1,200 cases reported since June, including 40 who were sick enough to require hospitalization.

Cyclospora cayetanensis is a tiny heat-loving parasite that infects the bowels and spreads through feces. Cases typically rise in spring and summer. The cyclosporiasis season runs from May 1 through Aug. 31.

Below are seven things Rhode Island residents need to know.

1. Why Is The Cause So Elusive?

Cyclospora surges can be tricky to investigate, and the source of foodborne illness can be hard to establish. But “there is clearly a linked outbreak happening right now,” Dr. Natasha Bagdasarian, Michigan’s chief medical executive, told The Associated Press.

Comprehensive data on cyclospora outbreaks is lacking. But available information shows only a small number of documented outbreaks in the last 20 years have surpassed 1,000 cases. That short list includes a 1997 outbreak tied to Guatemalan raspberries that sickened more than 1,000 in the U.S. and Canada, and a 2019 outbreak linked to Mexican basil that sickened more than 2,400.

There are several reasons it’s challenging to know the exact toll, Melanie Firestone, a University of Minnesota foodborne illness researcher, told the AP. Some tests used to check for types of food poisoning are not geared to detect cyclospora, “so there is a lot of underreporting when it comes to this,” she said.

Other challenges: Technicians aren’t able to grow the parasite in labs, making it hard to draw evidence from contaminated produce. And it can be hard to figure out what food sick people had in common, because sometimes it’s a single ingredient that might be common in multiple recipes — like basil or cilantro.

Also, it’s possible that food distributors may channel contaminated foods to both grocery stores and restaurants, making it hard to discern where tainted food came from. Investigations can take months and sometimes never find a clear source.

2. Why Hasn’t Anything Been Recalled?

No recall has been issued because investigators still haven't identified the food responsible for the outbreak.

Unlike outbreaks linked to a single packaged product, cyclospora outbreaks often involve fresh produce with a relatively short shelf life. By the time illnesses are reported, patients are interviewed, laboratory testing is completed and investigators identify foods people ate weeks earlier, the suspected produce is often no longer in stores or restaurants.

That’s one reason cyclospora investigations can take months and sometimes end without a definitive answer. Until a specific source is identified, health officials generally don't recommend avoiding any particular fruit or vegetable beyond routine food-safety precautions.

3. How Is It Spread?

Because cyclospora requires a one- to two-week period outside the body before it becomes infectious, food handlers who are infected are generally not considered the primary source of outbreaks simply by touching food.

That’s different from pathogens such as norovirus or hepatitis A, which can spread directly from an infected food worker to ready-to-eat foods. With cyclospora, investigators often look upstream in the growing and processing chain, especially at water quality and sanitation.

That doesn't necessarily mean someone relieved themselves in a field. Public health experts say contamination is more commonly associated with human sewage entering water supplies used to irrigate or wash crops, particularly in areas with inadequate sanitation or wastewater treatment.

It can also be spread by swimming in contaminated water. That includes not only lakes, but also chlorinated swimming pools and hot tubs. The parasite can survive chlorinated pool water for a long time, according to the Cleveland Clinic.

There have been links between some kinds of fresh produce and cyclosporiasis outbreaks. It may occur if you use contaminated water to grow or wash produce. Using poop to fertilize produce is also a risk.

4. Who’s Getting Sick?

According to the CDC, the 145 individuals identified in the current domestic tally range in age from 5 to 86 years old. With a median age of 42, approximately 61 percent of those affected are female.

The Cleveland Clinic describes the diarrhea caused by the infection as “explosive” and said it can last for months if it isn’t treated.

Other symptoms include loss of appetite, weight loss, stomach cramps, bloating, gas, nausea, fatigue and, occasionally, vomiting or low-grade fever, according to the CDC.

Additionally, officials have tracked 45 cases involving international travelers who contracted the illness from contaminated food or water while abroad. While three of those patients required hospitalization, no fatalities have been linked to the outbreak.

Cyclosporiasis symptoms may be more severe in people with a weakened immune system.

5. Is The Parasite Mutating?

There’s no evidence that the parasite has evolved to become more infectious, Dianna Blau, the CDC’s acting parasitic diseases branch chief, told the AP.

Thousands of cyclospora illnesses are reported in the U.S. each year, and it’s not yet clear how unusual this year will be, she added. That said, the case total so far is four times higher than at the same point last year, according to current CDC national data, which lags dramatically from what’s being reported by the states.

It’s less common than a number of other kinds of foodborne illnesses, including salmonella and E. coli. For years, few U.S. cyclospora outbreaks were reported each year. But the number started rising about a decade ago, with a particularly notable spike in 2018 and 2019. Experts attribute the increases to climate change and better detection.

6. Does Parasite Stay In Body?

Unlike some parasites that can remain in the body for years, Cyclospora cayetanensis infects the lining of the small intestine and is typically cleared with appropriate antibiotic treatment — Trimethoprim/sulfamethoxazole (TMP/SMX).

This treatment is typically accompanied by rest and drinking plenty of fluids to maintain proper hydration. If left untreated, the illness can drag on from a few days to more than a month, with symptoms that may go away and then return.

While cyclosporiasis is generally not life-threatening, the dehydration resulting from frequent diarrhea can cause severe illness, particularly among infants, young children, the elderly, and those with weakened immune systems.

7. What Should You Do?

People who have diarrhea that hasn’t gone away on its own within a few days should see a health provider and discuss the possibility of cyclospora, officials say.

Fresh produce should be thoroughly washed before being eaten. But be aware that cyclospora can really stick to some foods, so washing may not eliminate the risk of infection.

As Michigan officials investigate the potential source, they recommend consumers purchase whole heads of lettuce rather than prewashed, bagged lettuce or salad mixes and remove the outer two to three leaves before washing the remaining leaves under running water.

They also say to cook vegetables when possible.

The Associated Press contributed to this report.

See also:

• University Of Rhode Island Entomologist Devises Unique Approach To Combating Invasive Spotted Lanternfly
• Rhode Island Nearly The Worst State In America For Business
• Aquatic Weed Treatments Planned for 2 RI Ponds, 1 Lake
• Rhode Island's 1st 2026 West Nile Case Detected In Providence
• State Recommends Closing Down 3 Rhode Island Beaches To Swimming