See map tracking spread of ‘explosive’ diarrhea illness across US

Cases of the disease caused by a parasite that causes explosive diarrhea continue to spread across the United States, sickening hundreds of people in a surge that authorities are trying to track.

cyclosporiasis, A stomach-churning illness caused by a parasite often found in produce and herbs has sickened at least 843 people in 31 states since May 1, according to the U.S. Centers for Disease Control and Prevention and state health data. Michigan a group is fighting an infection This has already exceeded the total number of cases in 2025 by more than 14 times, while many others have reported numbers exceeding the hundreds.

Additional reports at the state level show a larger surge of cases not yet reflected in the CDC surveillance dashboard, which until this point has only been updated monthly. The latest data, released July 9, still lags government reports as the agency struggles to confirm infections. There is currently no evidence of a single source connecting the clusters of cases.

Here’s what you need to know since the CDC’s last update on June 16, which reflected just 145 cases in 18 states nationwide.

Monitoring the spread: Why is it difficult to trace the source of ‘explosive diarrhoea’?

What is cyclosporiasis? What are the symptoms?

Cyclosporiasis is a parasitic infection that causes uncomfortable gastrointestinal symptoms often associated with food poisoning, such as diarrhea, nausea, and vomiting. It is caused by the parasite Cyclospora cayetanensis, also known simply as cyclospora, and is usually transmitted through contaminated food.

While it can be unpleasant, it is not generally known to cause death, and many cases go unreported because people recover at home without seeing a doctor.

The most common symptom is watery, frequent and sometimes “explosive” diarrhea, according to the CDC. Cleveland Clinicbut other problems may include:

• Bloating or stomach cramps, including burping and gas

• Extreme tiredness (fatigue)

See a map of states with cyclosporiasis cases

The CDC tracks cyclosporiasis cases based on where and when they were contracted. As of July 9, 843 people in 31 US states have been infected since May 1. An additional 343 people, tracked and categorized separately, contracted the infection while traveling abroad.

Of the 843 people who got sick in the USA, 86 were hospitalized. None of them died. Cases were seen in people aged between 5 and 88, with an average age of 44. According to the CDC, the cyclosporiasis “season,” or months that typically see a spike in the disease in the United States, begins May 1 and lasts through the end of August.

But these numbers do not include hundreds more reported by individual states.

Why don’t the CDC numbers match what the states say?

Despite a recent update, the CDC’s numbers do not match those reported by individual states. For example, the CDC listed only 161 to 300 cases in Michigan as of July 9; however, state health officials reported a total of 700 cases to USA TODAY as of July 6.

The reason for this is simple: the CDC only reports laboratory-confirmed cases that occur on or after May 1 and are “confirmed domestically acquired”; This means patients did not travel internationally in the 14 days before they became ill. Many states, however, share data that includes year-to-date figures or does not differentiate between domestic and international infections.

“CDC recognizes that states will likely report higher cyclosporiasis case numbers than reflected in CDC data and is working closely with states to update the numbers as additional cases are confirmed,” the agency said in a statement on its report. he said. cyclosporiasis surveillance page. “Since May 1, 2026, CDC has received reports of 843 confirmed cases of domestic cyclosporiasis and is aware of more than 1,500 cases that require further analysis to confirm that the disease is domestically acquired cyclosporiasis.”

In other words, the agency knows there are more cases out there; It’s just a matter of waiting for the tests to come back. And even if states have hundreds of cases since the beginning of the year, the CDC won’t count them unless it can prove individuals contracted the disease after May 1.

“We assume a 6-week reporting lag between the onset of illness and reporting of cases to the CDC, so we anticipate case numbers will continue to increase as data is received,” the portal page states. The agency will also begin requesting state data on a weekly basis instead of monthly because cases are rising so quickly, he told USA TODAY.

See the states with the most: ‘Explosive’ diarrheal disease cases in top 1K

States reporting the highest numbers

Michigan’s more than 700 cases as of July 6 make it by far the state with the most infections, though others have reported numbers in the hundreds.

The Ohio Department of Health told USA TODAY that 364 cases of cyclosporiasis were recorded on July 9, and all but six of them occurred after May 1. All of the cases were acquired domestically, and 46 of them were hospitalized.

North Carolina told USA TODAY there were 205 cases between May 1 and July 9, while New York City recorded a total of 301 cases as of July 7, with 273 of those occurring since May 1. New York City’s count includes recent international travelers as well as those who may have contracted the disease domestically.

New York State, which reports and tracks infectious diseases separately from New York City, confirmed 120 cases between May 1 and July 7. It was not stated whether all reported cases came from the country. The state had relatively high case numbers in previous years; It ranged from 500 to 700 in 2024 and 2025.

How to avoid contracting a parasite that causes diarrhea?

Cyclosporiasis is transmitted via the fecal-oral route, meaning contact with food, drinks, and surfaces contaminated with infected poop particles. Often this means consuming the affected food or drink directly, or touching something contaminated and then touching your mouth without washing your hands.

According to the CDC, we often see an increase in cyclosporiasis infections during the hot summer months due to infected fecal matter contaminating fresh, summer produce like basil, raspberries, and lettuce, all of which have been linked to past U.S. outbreaks.

People usually become sick about a week after exposure, but symptoms can appear in as little as two days and up to two weeks later and beyond.

The infection is treated with antibiotics, and while most healthy people can probably fight it off on their own, long-term, untreated illness can last for months and recur, according to the CDC. As is often the case, children, the elderly, and those with compromised immune systems are more likely to become seriously ill or even die, and should contact a healthcare professional if they become ill.

To prevent contracting cyclosporiasis, first HKM, Cleveland Clinic And Michigan Department of Health I recommend you to:

• Avoid consuming food or water that may be contaminated with feces. Avoid drinking or cooking with unpurified water.

• Wash your hands with soap and water after using the bathroom and before, during and after preparing food.

• Wash all food preparation surfaces, including utensils, cutting boards, and counters, before and after use.

• Wash and peel vegetables before eating; Thoroughly scrub skinned produce such as melons and cucumbers; Cut off any damaged or bruised areas on fruits and vegetables before preparing and eating them.

• Store prepared fruits and vegetables in the refrigerator as soon as possible (within two hours).

This article first appeared on USA TODAY: See map tracing spread of ‘explosive’ diarrheal disease across US