The 2026 cyclospora outbreak has now been linked to two deaths in Michigan, the first confirmed fatalities in what has become one of the largest recorded outbreaks in the United States. As of August 2026, the Centers for Disease Control and Prevention has tallied 6,707 laboratory-confirmed cases across 45 states, though the true burden is likely much higher: Michigan alone has reported more than 11,000 suspected cases since June 22.
What we know about the deaths
The Michigan Department of Health and Human Services confirmed the two deaths on August 3, 2026. According to officials, both patients had significant underlying health conditions that may have been exacerbated by the severe dehydration common to cyclosporiasis. The CDC has acknowledged awareness of the deaths on its outbreak investigation page but has not released additional detail.
Cyclosporiasis is not typically fatal. But some groups are at higher risk of complications, including those with weakened immune systems, older adults, and young children. The illness can cause explosive watery diarrhea that persists for up to a month, and the resulting dehydration is the main pathway to severe complications, according to the Food and Drug Administration.
How the cyclospora outbreak grew
The outbreak has been linked to iceberg lettuce supplied to Taco Bell by Taylor Farms de Mexico, established through traceback investigation earlier this summer. However, officials have not ruled out additional sources of contamination, and the ongoing case growth suggests the outbreak may involve multiple pathways.
Case counts have climbed rapidly through July and into August. The CDC’s most recent national tally of 6,707 confirmed cases spans 45 states, up from 31 states reported earlier in the summer. Michigan has borne a disproportionate share: state health authorities have logged more than 11,000 cases since June 22. Most of these have not been laboratory-confirmed. The CDC’s national number reflects only cases with confirmed laboratory identification of the parasite, so the gap between Michigan’s total and the federal count is a reporting-methodology difference, not an inconsistency.
Natasha Bagdasarian, Michigan’s chief medical executive, told Scientific American that the number of infections this summer has far exceeded the normal seasonal load. Researchers had earlier told the magazine that cyclosporiasis cases typically decline in August. That pattern has not held this year.
How Cyclospora spreads
Cyclospora cayetanensis is a single-celled parasite spread through food or water contaminated with human feces containing the parasite’s oocysts. The oocysts must undergo maturation outside the body, a process called sporulation that takes one to two weeks under warm, moist conditions, before they can cause infection. Because of this delay, cyclosporiasis is not directly spread from person to person.
US outbreaks have historically been linked to fresh produce imported from regions where the parasite is endemic. Past outbreak sources have included imported raspberries, basil, cilantro, snow peas, and salad greens. Standard washing does not fully remove the parasite from produce surfaces, because oocysts can adhere firmly. Cooking to at least 160°F (71°C) kills the parasite, as does thorough freezing.
Symptoms and diagnosis
Symptoms typically begin about seven days after exposure, with a range of 2 to 14 days. The main symptom is watery, sometimes explosive diarrhea that is often prolonged and relapsing. Untreated, it can last for weeks or months. Other symptoms include loss of appetite, weight loss, stomach cramps, bloating, gas, nausea, fatigue, and low-grade fever.
Diagnosis requires specific laboratory testing. Cyclospora is not detected by routine stool cultures or standard multiplex molecular panels. Clinicians who suspect the infection must request testing for Cyclospora cayetanensis specifically. In the current outbreak, the CDC has explicitly asked providers to consider the test in patients with prolonged watery diarrhea, particularly after fresh produce consumption.
Treatment
Cyclosporiasis is treatable. First-line therapy is trimethoprim-sulfamethoxazole (TMP-SMX), a combination antibiotic that resolves symptoms within one to two weeks in most patients. Patients with sulfa allergies have limited alternatives; nitazoxanide has been used but with less consistent efficacy. Supportive care with rehydration and electrolyte replacement is important given the volume of fluid loss from prolonged diarrhea, particularly for older adults, young children, and immunocompromised patients.
What consumers should do
Until the full scope of contamination sources is identified, general food safety practices remain the best protection:
- Cook fresh produce to at least 160°F (71°C) for assurance of killing the parasite. Washing alone is not enough.
- Consider avoiding raw produce historically associated with outbreaks, including raspberries, basil, cilantro, snow peas, and salad greens, until the outbreak subsides.
- Follow CDC and FDA outbreak alerts for specific product recalls and named brands.
- Seek medical care for prolonged watery diarrhea lasting more than a few days, especially if it began after eating fresh produce. Ask specifically whether Cyclospora testing is available; the parasite is not detected by standard stool testing.
Why the response has been hampered
Two factors have complicated the outbreak response. In July 2025, the CDC removed cyclosporiasis from FoodNet, the systematic case-detection system that historically enabled national tracking. Cyclosporiasis remains a nationally notifiable disease, but active FoodNet surveillance became optional for state laboratories. As a result, the CDC’s national count likely underestimates the true burden. Michigan’s 11,000-case tally versus the national confirmed count of 6,707 illustrates the gap.
Reductions in the federal public health workforce during 2025 have also affected the CDC personnel who conduct traceback investigations for foodborne outbreaks. Traceback for parasitic outbreaks is already technically challenging: unlike bacterial pathogens, Cyclospora cannot be cultured, and whole-genome sequencing tools common in bacterial outbreak investigations are more limited for parasites.
The wider context
Cyclosporiasis has been rising in the United States since the mid-2010s. Domestic cases doubled from approximately 537 in 2016 to 1,194 in 2017, then tripled to 3,519 in 2018. Between 2019 and 2022, laboratory-confirmed cases ranged from a low of 1,024 in 2021 to a high of 2,408 in 2019. The 2026 outbreak, now the largest on record, marks a further escalation. The CDC has classified cyclosporiasis as an important neglected parasitic infection. Epidemiologists have warned that recurrent large summer outbreaks may signal progressive endemicity of the parasite in the United States.
The current outbreak is a reminder that the fresh produce supply chain remains vulnerable to parasitic contamination, and that scaling back active surveillance for pathogens difficult to trace by other means has real consequences. When outbreak sources cannot be identified quickly, exposures continue and case counts grow. That has been the pattern this summer, and it may become a more common one in years ahead if surveillance infrastructure is not restored.
References
- Kovac A. Cyclospora outbreak tied to two deaths as parasite-borne illness continues to rage. Scientific American, August 3, 2026. Available online.
- Centers for Disease Control and Prevention. Outbreak Investigation Notice: Cyclosporiasis linked to Taco Bell shredded iceberg lettuce, 2026. cdc.gov/cyclosporiasis/outbreaks/07-26.
- Michigan Department of Health and Human Services. Infectious Disease Outbreaks. michigan.gov/mdhhs.
- US Food and Drug Administration. Cyclospora. fda.gov/food/foodborne-pathogens/cyclospora.
- Kovac A. Cases of explosive-diarrhea-causing parasite cyclosporiasis are rising fast in the U.S. Scientific American, 2026. Available online.
- Centers for Disease Control and Prevention. Cyclosporiasis Surveillance. cdc.gov/cyclosporiasis/php/surveillance.