A parasitic infection causing explosive, relentless diarrhea has reached an unprecedented scale across the Midwest and several other U.S. states, and thousands of patients may be going undiagnosed because most standard laboratory stool tests cannot detect it.
Ohio has confirmed 177 cases of cyclosporiasis in 2026 — 171 of which appeared in less than two weeks, mostly since June 20, across 43 of the state's 88 counties, according to Ohio Department of Health Director Dr. Bruce Vanderhoff. Michigan has confirmed 708 cases as of July 7, 2026 — approximately 14 times higher than the state's annual average — concentrated in Southeast Michigan counties including Wayne, Monroe, Oakland, and Washtenaw. Nationally, the infection has been reported in Michigan, Ohio, Illinois, Indiana, New York, North Carolina, Texas, and other states.
And no common food source has yet been identified.
Why This Matters
Cyclosporiasis is frequently misdiagnosed — not because physicians lack clinical knowledge, but because the parasite does not appear on standard commercial stool panels. A doctor who orders a "routine stool culture" or a commercial stool diarrhea panel for a patient with prolonged watery diarrhea will almost certainly miss Cyclospora unless they know to order a specific test.
Pharmacy Times' July 9 clinical explainer confirms that clinicians must order modified acid-fast staining or PCR testing specifically for Cyclospora to detect the parasite. This is not automatic. It requires the ordering provider to suspect the diagnosis and request the right test by name.
The practical consequence: patients with cyclosporiasis may receive multiple rounds of antibiotics that do nothing, visit urgent care repeatedly without resolution, or simply endure weeks of symptoms while the infection is attributed to food poisoning, IBS, or viral gastroenteritis. The treatment exists and works, but it requires the correct diagnosis first.
What We Know So Far
Cyclospora cayetanensis is a microscopic, single-celled parasite that infects the small intestine. The CDC describes it as spread through the ingestion of food or water contaminated with feces from an infected person — the fecal-oral route. It is not spread directly from person to person.
The current outbreak by the numbers, as of July 7–9, 2026:
- Michigan : 708 cases confirmed as of July 7 , concentrated in Southeast Michigan. The state's annual average is 40–50 cases per year — making the current count roughly 14 times higher than normal. Dr. Natasha Bagdasarian, Michigan's chief medical executive , called the number a "moving target" and said cases are likely to continue rising.
- Ohio : 177 cases as of July 2 , confirmed across 43 of 88 counties. Lucas County in northwest Ohio leads with 30 cases, followed by Wood County with 20. The Ohio Department of Health confirmed 28 hospitalizations. Dr. Vanderhoff stated: "Fortunately, there have been no deaths in Ohio, as is consistent with our past experiences with this illness. Nevertheless, this is a serious illness that can cause dehydration and require people to seek emergency medical care, and it should be taken seriously."
- Illinois : 141 cases in 2026, "higher than average," with no single cause identified.
- Indiana : 72 cases since May 1.
- North Carolina : At least 110 infections since May.
- New York : 120 cases since May 1 (not unusually high for New York, which typically records 500–700 annually).
- Texas : Cases also reported, with CBS Texas issuing a health department advisory.
The CDC reports a national count of at least 145 cases acquired domestically between May 1 and June 16, 2026 — a partial accounting that significantly undercounts the current scale given Michigan's surge, which is not included in that figure.
Critically: No common food source has been identified across states. The CDC stated as of recent reporting that there is "no evidence of a single, multistate Cyclospora outbreak linking all cases." The FDA said it is "not in a position at this time to characterize the current numbers as definitively unusual pending the completion of that investigation." State health departments are actively conducting traceback investigations.
Where the Risk Is Highest
Southeast Michigan is the current national epicenter. The counties with the highest case concentrations are Monroe, Lenawee, Washtenaw, Wayne (where Detroit is located), Shiawassee, Jackson, Oakland, and Livingston.
Northwest Ohio has the highest within-state concentration, with Lucas County (Toledo) and Wood County accounting for 50 of the state's 177 cases.
The broader Midwest regional pattern — Michigan, Ohio, Indiana, and Illinois all reporting above-average or unprecedented case counts — is consistent with a shared regional food supply chain exposure, though investigators have not confirmed a single source.
Nationally, prior Cyclospora outbreaks in the U.S. have been traced to fresh produce including raspberries, bagged salad mix, cilantro, fresh basil, and snow peas — typically imported from countries where Cyclospora is endemic. The 2013 outbreak was linked to bagged salad mix; the 1996–1997 outbreak was linked to Guatemalan raspberries. Michigan's MDHHS has shared this list of produce categories with the public as a precautionary reference while the investigation continues.
The Critical Clinical Education Point: Standard Tests Do Not Detect Cyclospora
This is the most important health information in this article.
If you have had prolonged or relapsing watery diarrhea — lasting more than a week, or that seems to improve and then return — and you have not specifically been tested for Cyclospora, you may not have been tested for it at all.
Standard stool cultures identify bacterial pathogens like Salmonella, Campylobacter, and Shigella. Commercial stool diarrhea PCR panels (such as the BioFire FilmArray GI panel) detect a range of bacterial, viral, and parasitic pathogens — but do not reliably detect Cyclospora or do not include it at all in standard configurations.
Pharmacy Times confirmed that clinicians must order one of two specific tests:
- Modified acid-fast staining of a stool specimen — a microscopy technique that identifies the distinctive appearance of Cyclospora oocysts
- PCR testing specifically for Cyclospora cayetanensis — a molecular test that must be explicitly ordered
Neither test is automatic. The ordering provider must suspect cyclosporiasis and specifically request the right test. During an outbreak of this scale, any patient in an affected state with prolonged diarrhea — particularly diarrhea that has persisted beyond 7 to 10 days or relapsed after seeming to improve — should tell their provider about the ongoing outbreak and ask specifically for Cyclospora testing.
What Doctors and Experts Say
Dr. Natasha Bagdasarian, Michigan's chief medical executive and an infectious disease physician and epidemiologist, described the 678-figure (now updated to 708) as a moving target and said officials expect cases to continue rising. She stated that the most common symptoms — explosive, watery diarrhea and GI cramping — typically begin 7 to 14 days after exposure, making early identification and traceback complex.
Ohio Department of Health Director Dr. Bruce Vanderhoff emphasized that while no deaths have occurred in Ohio, cyclosporiasis should not be taken lightly: "This is a serious illness that can cause dehydration and require people to seek emergency medical care." He confirmed that ODH and local health departments are coordinating with neighboring states and federal partners to identify any common exposures.
Regarding produce safety, Dr. Kaminski, quoted by NBC News via MedicalDaily.com, noted that "raspberries in particular can be difficult to clean because they are covered in tiny hairs that the parasite likes to hang on." Michigan MDHHS advises that cooking food to 158°F or higher will kill Cyclospora — standard rinsing reduces but does not eliminate risk.
What the Evidence Shows and What It Does Not
The CDC has not confirmed a single food source linking all current U.S. Cyclospora cases. The investigation is ongoing. The co-occurrence of high case counts in Michigan, Ohio, Indiana, and Illinois may reflect a shared regional exposure — or multiple independent exposure events occurring during the same seasonal Cyclospora window (typically May through August).
The CDC's stated 145-case national count (through June 16) does not include Michigan's cases, which emerged primarily after June 22. The actual national total as of July 9 is likely well over 1,000 cases when all state-reported figures are combined.
Cyclosporiasis is not typically life-threatening in healthy adults — but it is not a self-limiting 24-hour illness. Without treatment, the infection can persist for weeks, with symptoms that relapse and remit. Hospitalization rates are meaningful: Ohio confirmed 28 hospitalizations out of 177 cases — approximately 16%.
Who Faces the Greatest Risk?
According to CDC guidance on cyclosporiasis:
- People who eat fresh produce frequently , particularly raspberries, bagged salads, cilantro, or other fresh herbs — especially if imported
- People living or working in or visiting Southeast Michigan, northwest Ohio , or other areas with active case clusters
- Immunocompromised individuals , including those with HIV/AIDS, on cancer treatment, or taking long-term steroids — these patients can develop more severe, recurring infections that require extended treatment
- Children who develop diarrhea and may not be able to communicate the severity of symptoms
- Anyone who has had prolonged diarrhea since late May 2026 and has not been specifically tested for Cyclospora
Symptoms and Warning Signs to Watch For
Cyclosporiasis has a longer incubation period than most foodborne illnesses. Symptoms typically begin 7 to 14 days after ingesting contaminated food or water — meaning the exposure may feel entirely disconnected from when illness begins.
Primary symptoms include:
- Watery, sometimes explosive diarrhea — often the dominant symptom
- Frequent, unpredictable bowel movements
- Nausea, sometimes vomiting
- Loss of appetite and weight loss
- Abdominal cramping and bloating
- Fatigue and general malaise
- Low-grade fever
- Flu-like muscle aches
A distinctive clinical feature: cyclosporiasis often relapsing.Symptoms may appear to resolve and then return — sometimes repeatedly — without treatment. This cycle-within-illness pattern gives the parasite its name and is one of the key diagnostic clues.
If you have had watery diarrhea lasting more than seven days — or diarrhea that keeps coming back — especially in the past several weeks and especially if you live in Michigan, Ohio, Indiana, or Illinois, tell your doctor specifically about the ongoing outbreak and ask to be tested.
What You Can Do Now
- If you have prolonged or relapsing diarrhea , contact your healthcare provider. Do not self-treat with over-the-counter anti-diarrheal medications without medical guidance — these can complicate diagnosis.
- Tell your provider about the outbreak and ask specifically for Cyclospora testing. The exact request is: "I would like to be tested for Cyclospora cayetanensis — I understand this requires a modified acid-fast stain or a specific PCR test for Cyclospora."
- Do not rely on a standard stool culture to rule out Cyclospora. It cannot.
- Regarding fresh produce: Until a food source is identified, consider the following precautions for higher-risk items: thoroughly rinse fresh raspberries, strawberries, lettuce, cilantro, and fresh herbs under running water. Buy whole heads of lettuce rather than pre-cut bags when possible. Remove outer leaves before washing.
- Cook produce to 158°F to kill the parasite. This applies to dishes where produce is cooked rather than eaten raw.
- Stay hydrated. The biggest short-term risk from cyclosporiasis is dehydration. If you cannot keep fluids down, seek medical care rather than waiting.
- If you are immunocompromised and develop diarrhea , seek medical evaluation sooner rather than later — this group is at risk for more severe and prolonged infection.
Cost and Access: What Patients Should Know
The treatment for confirmed cyclosporiasis is trimethoprim/sulfamethoxazole (TMP-SMX), a combination antibiotic (brand names Bactrim or Septra) that is inexpensive and widely available as a generic. The CDC recommends a 7-to-10-day course for most otherwise healthy adults. Patients who are allergic to sulfa drugs should discuss alternatives with their provider, as there is no established alternative regimen.
Testing for Cyclospora may require a specific laboratory request and may not be covered by all insurance plans at routine visit copay rates. Patients can ask their provider whether the test will be billed as part of their existing visit or separately.
For patients without insurance, community health centers and county health departments in Michigan, Ohio, Illinois, and Indiana are providing guidance during the outbreak. Ohio residents can also contact the Ohio Department of Health directly at odh.ohio.gov.
What Happens Next
Ohio and Michigan are conducting active traceback investigations in coordination with the CDC and FDA. As of July 9, no recall has been issued, and no specific food product has been publicly identified as a source. The FDA confirmed it is monitoring the situation and is in contact with state health departments.
Michigan MDHHS has asked residents who purchased or consumed fresh produce within the past month to report their purchases as part of the investigation. Check michigan.gov/mdhhs and odh.ohio.gov for updates.
The Cyclospora season in the United States typically runs through August. Case counts may continue to rise before a source is identified and controlled.
MedicalDaily will update this article as additional states confirm above-average case counts or a food source is identified.
The Bottom Line
A Cyclospora outbreak has infected more than 700 people in Michigan, 177 in Ohio, and hundreds more across the Midwest and other states — with no food source yet identified and no recall issued. The most critical information for readers: standard stool tests do not detect Cyclospora. If you have had prolonged or relapsing diarrhea in the past few weeks — especially in an affected state — contact your healthcare provider and specifically request a modified acid-fast stain or Cyclospora PCR test by name.
The treatment is straightforward once the diagnosis is made. The diagnosis requires asking for the right test.
