The U.S. Centers for Disease Control and Prevention have linked cases of an intestinal parasite that causes explosive diarrhea in Ohio and three other states amid a nationwide outbreak, the agency reported July 14.
Ohio, Michigan, West Virginia and Kentucky have reported more than 400 people with cyclosporiasis, a gastrointestinal illness caused by a parasite known as cyclospora cayatenensis, to the CDC as of July 13, with additional cases still under investigation in the multistate outbreak.
The CDC’s numbers differ from what states are reporting. The Ohio Department of Health reported 364 cases in the state when the department last updated the numbers on July 9, while Michigan health officials say at least 2,640 people have been sickened there.
While the CDC says a specific food item has not yet been confirmed as the source, Michigan investigators say they are zeroing in on lettuce and other salad greens, the Detroit Free Press reported July 13. However, other types of food items cannot be completely ruled out and no specific type of produce, grower or supplier has been identified as the source.
Ohio cyclospora outbreak cases double in week
The Ohio Department of Health reported 364 cases of cyclosporiasis in 51 counties in the state so far in 2026 as of July 9, with 46 people hospitalized. That’s up from 177 in 43 counties the previous week. All but six of those cases occurred in June and July, mostly since June 20. The gastrointestinal illness is caused by a parasite known as cyclospora cayatenensis.
The most cases in Ohio are in Lucas County in the northwest portion of the state, which reports 86, up from 30 the previous week. Wood County, just to the south of Lucas, reports 49 cases, up from 20.
Nationally, NBC News and Today’s tally of state reports found more than 4,000 reported cases nationwide as of July 13, 2026. The CDC, however, is reporting 1,645 confirmed cases with another 5,100 that require more analysis before they are confirmed.
Which states have identified cases of cyclosporiasis?
The actual number of cyclosporiasis infections is likely higher than reported, as many people recover without seeking medical care and therefore are never tested for cyclosporiasis.
Michigan, New York, Ohio, Illinois and North Carolina are among the states reporting the highest numbers of cases of the parasitic illness, according to NBC News.
What is cyclosporiasis? Illness from cyclospora cayatenensis parasite causes explosive diarrhea
Cyclosporiasis is an intestinal illness caused by the microscopic parasite cyclospora cayetanensis, also known as cyclospora, according to the CDC. The illness is not usually life-threatening.
The parasite spreads when people eat food or drink water that was contaminated with feces. People may be at an increased risk for infection when living or traveling in tropical or subtropical regions of the world where cyclosporiasis regularly occurs.
In the U.S., outbreaks of cyclosporiasis have been linked to various types of fresh produce.
How is cyclosporiasis treated? With Bactrim? Does it clear up on its own?
According to the CDC, Trimethoprim-sulfamethoxazole (TMP-SMX), which is sold under the brand names Bactrim, Septra or Cotrim, is the treatment of choice for the illness caused by the parasite.
Sulfamethoxazole and trimethoprim are types of antibiotics used to treat bacterial infections, according to the Cleveland Clinic. Available as a tablet, it belongs to a group of medications called sulfonamide antibiotics.
A cyclosporiasis infection can often clear up on its own in healthy individuals, though symptoms may last several weeks.
How do I know if I have cyclosporiasis? Symptoms, testing
Symptoms of cyclosporiasis may include:
Less common symptoms may include:
Symptoms begin about a week after being infected and can last anywhere from a few days to a month or longer without treatment. Some symptoms, such as diarrhea, may go away and then return.
The illness is diagnosed by testing stool samples, according to the CDC.
Cyclosporiasis foods to avoid. How to wash produce to avoid cyclosporiasis
The CDC says the best way to prevent cyclosporiasis is to avoid food or water that may be contaminated with feces.
And to help do that, the agency recommends safe food-handling practices when dealing with produce, including:
Previous outbreaks tied to produce
In the past, outbreaks in the United States and Canada have been tied to bagged salad mixes and kits, such as precut lettuce blends with romaine, iceberg, red cabbage and carrots; fresh cilantro, basil, raspberries, snow peas and green onions.
Among them were outbreaks identified:
Kristen Jordan Shamus of the Detroit Free Press contributed to this report.
This article originally appeared on The Columbus Dispatch: CDC links cyclospora parasite outbreak cases in Ohio, 3 other states
Reporting by Chad Murphy, USA TODAY NETWORK / The Columbus Dispatch
USA TODAY Network via Reuters Connect
By Chad Murphy, USA TODAY NETWORK | USA TODAY Network
