Need to Know

• Michigan’s early investigation identified iceberg lettuce as a strong epidemiologic indicator, with 65.4 percent of patients with available food histories reporting iceberg lettuce consumption
• Nearly 70 percent of interviewed Michigan patients reported eating at a single restaurant chain, and 89.5 percent of an early subset consumed menu items containing iceberg lettuce
• Real-time epidemiologic data from Michigan helped guide public health actions and FDA’s lettuce traceback investigation, which ultimately implicated Taylor Farms iceberg lettuce from Mexico in the nationwide outbreak.

Nationwide Outbreak and Cyclosporiasis Surge Details

Since cyclosporiasis cases began increasing in Michigan and across the U.S. at the start of summer, the U.S. Food and Drug Administration (FDA) has identified a large outbreak cluster and implicated iceberg lettuce grown in Mexico and supplied by Taylor Fresh Foods/Taylor Farms as the vehicle of illness. As of August 28, the official nationwide outbreak count reached 11,458 illnesses across 20 states, per the U.S. Centers for Disease Control and Prevention (CDC).

Illnesses associated with the Taylor Farms lettuce outbreak represent only a portion of the unusually large number of cyclosporiasis cases reported across the U.S. in 2026. Between May 1 and August 31, CDC received reports of 19,595 laboratory-confirmed, domestically acquired cases, resulting in 1,043 hospitalizations and two deaths. For comparison, 1,180 cases were reported in the U.S during the same period in 2025. This total includes the cases associated with the Taylor Farms lettuce outbreak, other outbreaks, and non-outbreak-associated cases; however, the two reported deaths are associated with the outbreak and occurred in Michigan.

Michigan has continued to report thousands of additional illnesses since the period analyzed in the paper. As of September 7, the state reported 14,718 cyclosporiasis cases, 366 hospitalizations, and two deaths.

Michigan’s Epidemiologic Investigation Pointed to Iceberg Lettuce

Michigan typically reports only 40–50 cyclosporiasis cases annually. However, during June 21–27, 2026, MDHHS identified 58 cases, prompting an outbreak investigation. By July 22, 6,065 confirmed and probable cases had been reported across 69 of Michigan's 83 counties, with illness onset dates ranging from May 10–July 18.

Of the 3,114 patients interviewed by Michigan investigators, 2,168 (69.6 percent) reported eating food purchased from a single restaurant chain, referred to in the report as "Chain A." (Although unnamed in Michigan’s interim report, on July 17, FDA named Taco Bell as a restaurant chain where many of the cyclosporiasis outbreak patients in Michigan and other Midwestern states reported eating iceberg lettuce. Taylor Farms was the lettuce supplier to the Taco Bell locations where patients dined).

Chain A used a limited variety of uncooked produce, with lettuce being the most commonly consumed among interviewees. Among an early subset of 190 patients who had eaten Chain A menu items, 170 (89.5 percent) reported consuming a menu item containing iceberg lettuce.

For comparison, Michigan surveillance data from 2022–2025 showed that only 2.2 percent of confirmed cyclosporiasis patients without recent international travel had reported eating at Chain A establishments.

Evidence also pointed to lettuce exposure among people who had not eaten at Chain A. Among 700 of these patients for whom iceberg lettuce exposure information was available, 370 (52.9 percent), reported consuming iceberg lettuce. Across all patients with relevant food history data, 65.4 percent reported eating iceberg lettuce, while 83.2 percent reported consuming any type of lettuce.

Based on the findings, the authors identified iceberg lettuce at Chain A as a "strong epidemiologic indicator," while stressing that other exposure pathways could not be excluded.

Michigan Data Helped Inform Public Health Response, FDA Traceback

The report said that Michigan's epidemiologic findings informed FDA's traceback investigation of lettuce during the first weeks of the outbreak.

The authors noted that Cyclospora contamination typically occurs during farming or processing, after which contaminated produce can be distributed to multiple destinations. The two distinct peaks in Michigan illness onset dates suggested either two separate batches of contaminated produce or a single contaminated lot with staggered distribution. Additionally, shared contamination sources were suggested by the coinciding illness-onset dates for patients with and without exposure to Chain A.

FDA later announced a recall of Taylor Farms iceberg lettuce from central Mexico due to possible Cyclospora contamination. The agency subsequently began onsite inspections and sampling at Mexican growing and processing operations involved in the outbreak investigation.

“In this investigation, real-time interview data have helped guide public health responses,” the authors concluded. MDHHS notified CDC of the increase in cyclosporiasis cases on June 25 and issued a public alert on July 1. A July 4 alert provided food safety recommendations for restaurants and the public, after which several restaurants voluntarily removed specific ingredients from their menus. On July 13, MDHHS issued another alert warning of possible lettuce contamination.

The report authors disclaimed that the interim analysis is descriptive and should not in itself be interpreted as confirming an outbreak vehicle.