1,562 cases in Michigan. 843 confirmed nationally across 31 states. The source is unidentified. Here is what you need to know — and what to do right now.
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Infectious Diseases in Focus →In the summer of 2026, a microscopic parasite is causing one of the largest foodborne illness outbreaks in recent American history. As of July 10th, Michigan alone has reported 1,562 confirmed cases of cyclosporiasis — an infection caused by the parasite Cyclospora cayetanensis — in what amounts to more than 30 times the state's normal annual case count. Cases have been reported in 31 states, with 86 hospitalizations and no deaths.
The source of the outbreak has not been identified. Federal and state investigators have multiple active investigations open, but no specific food, supplier, restaurant, or brand has been publicly named as the cause. This article explains what the parasite is, how it spreads, what illness it causes, and — most practically — what you can do to reduce your risk right now.
| Location | Cases | Notes |
|---|---|---|
| Michigan (MDHHS) | 1,562 | 30x normal annual rate of ~50. Concentrated in SE Michigan: Wayne, Monroe, Lenawee, Washtenaw, Oakland, Ingham counties. |
| CDC National (31 states) | 843 confirmed | 86 hospitalizations, 0 deaths. CDC acknowledges real count is likely much higher. |
| Ohio (Northwest / Lucas County) | 500+ / 306 | Sharp rise since mid-June. |
| New York City | 372 | NYC Health Department independent count; higher than CDC figure for NY. |
Cyclospora cayetanensis is a single-celled parasite — a coccidian protozoan — that infects the lining of the small intestine in humans. It was first described as a human pathogen in the 1970s and has caused recurring outbreaks in the United States since the 1990s, frequently linked to fresh produce imported from regions where the parasite is endemic.
The parasite completes its life cycle within human intestinal cells, causing inflammation and damage to the intestinal lining that produces the characteristic prolonged, watery diarrhea of cyclosporiasis.
Cyclospora spreads through the ingestion of food or water contaminated with human feces containing the parasite in its oocyst form. The critical biological feature that distinguishes it from many other foodborne pathogens is the maturation requirement: oocysts shed in human stool are not immediately infectious. They require one to two weeks outside the body — in warm, moist conditions — to sporulate and become capable of causing infection.
Foods previously linked to Cyclospora outbreaks in the United States include bagged salad mixes and pre-cut lettuce blends, fresh cilantro, raspberries, basil, snow peas, and other raw produce. The common thread is fresh produce consumed raw, where contamination typically occurs through irrigation water, soil, or poor hygiene during harvesting, packing, or distribution.
The specific source of the 2026 outbreak has not been publicly identified as of July 10th. The FDA has opened four active investigations, with two reference numbers added on July 8th alone, both involving products described as "not yet identified." Some Metro Detroit Taco Bell locations were reported to have proactively removed raw ingredients — including lettuce, cilantro, onion, pico de gallo, and guacamole — from their menus, but no causal connection has been publicly established.
The incubation period for cyclosporiasis is approximately one week after ingesting contaminated food or water. Symptoms include:
Watery diarrhea — often explosive and frequent, which is the hallmark symptom. Severe abdominal cramps and bloating. Nausea and sometimes vomiting. Loss of appetite. Profound fatigue — which many patients describe as disproportionately severe relative to what they might expect from a gastrointestinal illness. Low-grade fever.
One of the defining features of cyclosporiasis — and one that distinguishes it clinically from many other foodborne illnesses — is its tendency to relapse. Patients may experience a period of improvement, followed by recurrence of symptoms. Without treatment, the illness can persist and relapse for weeks to months, making it genuinely debilitating in a way that interferes with work, travel, and normal daily activity.
Cyclosporiasis is treatable with antibiotics. The standard regimen is trimethoprim-sulfamethoxazole (TMP-SMX) — sold under the brand names Bactrim, Septra, and Cotrim — taken orally for 10 days. With appropriate treatment, most patients recover fully. There is currently no well-established alternative antibiotic regimen for patients who cannot take TMP-SMX; consultation with an infectious disease specialist is recommended for those cases.
If you develop prolonged or relapsing watery diarrhea — particularly with significant fatigue or loss of appetite — contact your healthcare provider. Be specific: tell them you are concerned about cyclosporiasis given the current outbreak, and ask them to order a stool test that specifically includes Cyclospora. Early diagnosis and treatment significantly shortens the illness and prevents weeks of debilitating relapsing symptoms.