Number of cases of parasite infection causing diarrhea explode in Ohio
- An outbreak of the intestinal parasite cyclosporiasis is affecting multiple states, with a significant number of cases in Ohio.
- The illness is caused by consuming food or water contaminated with feces, with outbreaks often linked to fresh produce.
- Symptoms include explosive diarrhea, loss of appetite, and cramping, which can last for weeks without treatment.
A nationwide outbreak of an intestinal parasite that causes explosive diarrhea is has exploded in Ohio.
The Ohio Department of Health is reporting 177 cases of cyclosporiasis, a gastrointestinal illness caused by a parasite known as cyclospora cayatenensis, in 43 counties so far in 2026. Of those, 171 cases occurred in June, mostly since June 20, ODH spokesman Ken Gordon said in a statement on July 2.
The most cases in Ohio are in Lucas County in the northwest portion of the state, which reports 30. Wood County, just to the south of Lucas, reports 20 cases. Just over the state line from Lucas County, Michigan is reporting more than 225 cases in 21 counties since June 22, the Detroit Free Press, part of the USA TODAY Network, reported July 1.
Nationwide, the U.S. Centers for Disease Control and Prevention reports that 145 people in 17 states reported cases of cyclosporiasis in the period between May 1 and June 16, 2026.
"ODH and local health departments are working with neighboring state partners, including Michigan, and federal partners to investigate. This includes conducting interviews to help identify any potential common exposures. At this point, no source has been confirmed," Gordon said.
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 is regularly occurring.
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.
Which Ohio counties are hit by cyclosporiasis?
These are the counties reporting cyclosporiasis cases as of July 2, and the number of cases, according to ODH:
- Allen: 1
- Ashland: 7
- Auglaize: 1
- Carroll: 3
- Clark: 2
- Clermont: 1
- Crawford: 7
- Cuyahoga: 4
- Fairfield: 3
- Franklin: 10
- Fulton: 5
- Greene: 3
- Hamilton: 5
- Henry: 2
- Holmes: 1
- Jackson: 2
- Jefferson: 1
- Knox: 1
- Lake: 4
- Lawrence: 1
- Licking: 7
- Lorain: 4
- Lucas: 30
- Mahoning: 2
- Marion: 1
- Medina: 2
- Montgomery: 4
- Morrow: 2
- Ottawa: 2
- Pickaway: 2
- Portage: 1
- Preble: 1
- Richland: 3
- Ross: 4
- Sandusky: 2
- Seneca: 2
- Stark: 8
- Summit: 3
- Tuscarawas: 1
- Warren: 1
- Williams: 1
- Wood: 20
- Wyandot: 10
What are the symptoms of cyclosporiasis?
Symptoms of cyclosporiasis may include:
- Explosive, watery diarrhea (most common)
- Loss of appetite
- Weight loss
- Cramping
- Bloating
- Increased gas
- Nausea
- Fatigue
Less common symptoms may include:
- Vomiting
- Body aches
- Headache
- Low-grade fever
- Other flu-like symptoms
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.
How to prevent 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:
- Wash hands with soap and water before and after handling or preparing raw fruits and vegetables.
- Wash all fruits and vegetables thoroughly under running water before eating, cutting or cooking.
- Scrub firm fruits and vegetables, such as melons and cucumbers, with a clean produce brush.
- Cut away any damaged or bruised areas on fruits and vegetables before preparing and eating.
- Refrigerate cut, peeled, or cooked fruits and vegetables as soon as possible (within two hours).