The CDC is issuing clinical alerts to healthcare workers across the country, warning them that a parasitic intestinal illness is circulating and that the standard test ordered for diarrheal illness will not detect it.
The Centers for Disease Control and Prevention has tracked 145 confirmed domestically acquired Cyclosporiasis cases in 17 states as of June 16, 2026. Michigan, not yet included in the federal count, has confirmed more than 300 cases in 7 Southeast Michigan counties as of July 3. The national case total is almost certainly substantially higher than any confirmed count, because most infected patients are never properly tested.
The reason for the diagnostic gap is specific and fixable: a routine stool culture — the default test ordered when a patient presents with acute diarrhea — does not detect Cyclospora cayetanensis. Identifying this parasite requires a separately ordered modified acid-fast stain or a Cyclospora-specific PCR. Without that specific order, a patient with Cyclospora will receive a negative stool test result and be sent home with an incorrect diagnosis.
Why This Matters
Cyclosporiasis does not resolve on its own in most patients. Unlike many common GI viruses that clear within a few days, Cyclospora infection typically produces weeks of recurring, relapsing diarrhea that can continue for months without antibiotic treatment. The effective treatment — generic trimethoprim-sulfamethoxazole (Bactrim) — is inexpensive and widely available, but it cannot be prescribed unless the correct diagnosis is made first.
A patient who has been told their stool test was negative, and their illness is "probably viral," may still have undiagnosed Cyclospora. If their diarrhea has persisted or returned since May 2026, particularly in Michigan, New York, Texas, or Illinois, they should specifically request Cyclospora testing.
What We Know So Far
From CDC's Cyclospora surveillance page, Michigan MDHHS, and Infection Control Today's July 7, 2026 clinical alert:
- CDC confirmed national cases (as of June 16, 2026) : 145 in 17 states
- Michigan cases (as of July 3, 2026) : More than 300 in 7 Southeast Michigan counties — not yet included in the federal 17-state count
- Patient profile : Ages 5 to 86; median age 42; 61% female
- Hospitalizations : 20 confirmed nationally
- Deaths : None reported
- Illness onset dates : May 1 through June 7, 2026
- Travel-associated cases : 45 confirmed separately (international travel)
- Domestic cases : 45 of the 145 domestic cases involved no international travel, confirming a U.S. food source
- Food source : Not yet identified; investigation ongoing
- The CDC explicitly notes that standard stool cultures do not detect Cyclospora and that clinicians must specifically order the appropriate test
Where the Risk Is Highest
Southeast Michigan represents the most concentrated cluster of Cyclospora cases in the United States as of this writing. Monroe County leads with approximately 67 confirmed cases; Wayne County (including Detroit) is also included in the outbreak zone, along with Lenawee, Washtenaw, Livingston, Shiawassee, and Jackson counties.
Nationally, New York leads state confirmed counts (approximately 80 cases), followed by Illinois and Texas. Florida, Georgia, Ohio, Pennsylvania, Connecticut, and several other states also have confirmed cases.
The geographic distribution — multiple states, no single city dominating — is consistent with a contaminated produce item distributed nationally rather than a localized restaurant or food service exposure.
What the CDC and MDHHS Say
"We currently have [hundreds] of cases and we are currently investigating the source. This is caused by an intestinal parasite — it's from contaminated food," Monroe County Health Department spokesperson Lindsay Patrick told WXYZ Detroit in a July 1 statement.
Dr. Natasha Bagdasarian, Chief Medical Executive at MDHHS, said: "Outbreaks of cyclosporiasis have been occurring across the United States and now here in Michigan. Based on the unusual number of cases we have identified in a little over a week, we anticipate additional cases of illness being reported."
The Infection Control Today clinical alert of July 7, 2026 emphasizes the same point for healthcare providers: the diagnostic gap is the single most important target for intervention in this outbreak.
What the Evidence Shows — and What It Does Not
The CDC has explicitly stated there is no evidence of a single unified outbreak linking all 145 cases nationally. The Michigan cluster appears to be a distinct regional outbreak — possibly from a different food product or supply chain than the national pattern. Both investigations are ongoing.
No specific food product has been identified or recalled. Without a recall, public health guidance remains general: exercise caution with fresh produce — particularly leafy greens, herbs (cilantro, basil), and salad mixes — and wash all produce thoroughly.
MedicalDaily Evidence Check
- Investigation type : Active multistate outbreak investigation (CDC and state health departments)
- National confirmed cases : 145 (as of June 16, 2026)
- Michigan cases : 300+ (as of July 3, 2026; not in federal count)
- Pathogen : Cyclospora cayetanensis (intestinal parasite)
- Critical diagnostic limitation : Standard stool cultures do NOT detect Cyclospora
- Correct test : Modified acid-fast stain OR Cyclospora-specific PCR — must be ordered by name
- Treatment : Trimethoprim-sulfamethoxazole (Bactrim) — effective, inexpensive, requires prescription
- What it does not show : Specific food source; investigation ongoing
Who Faces the Greatest Risk?
- Residents of Southeast Michigan who consumed fresh produce in late May or June 2026
- Anyone nationally who has had prolonged or recurring watery diarrhea since May 2026 and tested negative on a standard stool culture
- Immunocompromised individuals, in whom Cyclospora produces more severe and prolonged disease
- Older adults
Symptoms and Warning Signs to Watch For
Cyclospora infection produces:
- Frequent, sometimes explosive watery diarrhea — the hallmark symptom
- Cramping and bloating
- Nausea and loss of appetite
- Fatigue and muscle aches
- Low-grade fever
The most diagnostically important pattern: symptoms that wax and wane— improving for a few days, then returning. This recurring pattern strongly suggests Cyclospora rather than viral gastroenteritis, which typically resolves in 3 to 5 days.
What You Can Do Now
- If you have had prolonged or recurring diarrhea since May 2026 — particularly in Michigan, New York, Illinois, Texas, or Ohio — contact your healthcare provider.
- Tell your doctor specifically : "I want to be tested for Cyclospora. I need a modified acid-fast stain or a Cyclospora PCR — not just a routine stool culture."
- If you previously had a negative stool test but symptoms have persisted or returned, go back and specifically request Cyclospora testing.
- Wash all fresh produce thoroughly , especially leafy greens, cilantro, basil, and salad mixes, until a food source is identified.
- If you are immunocompromised , be especially cautious with fresh herbs and pre-cut produce.
Cost and Access: What Patients Should Know
Cyclospora-specific testing must be ordered separately from a routine stool panel. The test is covered by most insurance plans. Generic trimethoprim-sulfamethoxazole (Bactrim) is available at most pharmacies for under $10 with a GoodRx discount.
For patients without a primary care provider, urgent care clinics and community health centers can order Cyclospora-specific stool testing.
What Happens Next
The FDA and CDC are continuing traceback investigations into the food source. Michigan's MDHHS is conducting its own parallel investigation in Southeast Michigan. The summer Cyclospora season runs through August — additional cases are expected. MedicalDaily will report immediately when a food source is identified or a recall is issued.
The Bottom Line
A parasitic outbreak is spreading across Michigan and nationally, and most infected patients are being told their stool tests are negative — because the standard test cannot detect this parasite. The diagnostic gap is the most important clinical target in this outbreak. If you have had prolonged, recurring watery diarrhea since May, the specific instruction is this: ask your doctor for a modified acid-fast stain or Cyclospora PCR, by name, not a routine stool culture. Effective treatment exists and works quickly once the correct diagnosis is made.
