Lettuce Under Suspicion in Michigan Over Diarrhea Outbreak

A diarrhea outbreak caused by the parasite Cyclospora is concerning health authorities. Cases have already surpassed 3,000 between Michigan and Ohio. The ongoing investigation points to lettuce as a possible source.

However, Michigan health officials are exercising caution about the exact cause. They are not ruling out other foods as the source of contamination. No specific type, producer, or supplier responsible has been identified.

Dr. Natasha Bagdasarian, executive medical director of Michigan, explained the current situation. “Preliminary information indicates that lettuce is a common product”, she stated Monday. She assured that this vegetable appears frequently during the ongoing investigation.

Michigan and Ohio, the Hardest Hit States

Michigan reported 2,640 confirmed cases through 9:30 a.m. Monday. Of that total, 44 people required hospitalization due to complications from the illness. Ohio, meanwhile, has accumulated 361 cases since June 1st.

In Ohio territory, at least 46 additional hospitalizations were recorded. As of July 10, 31 states had reported cases nationwide. However, it is unclear whether all cases belong to the same outbreak.

The Centers for Disease Control and Prevention confirmed a recent increase. Several states reported more cases in the past two weeks compared to 2025. The national count, with 843 cases, is lower than that of individual states.

An Outbreak Difficult to Trace

Investigators face serious obstacles in determining the exact origin of the outbreak. The count of cyclosporiasis cases advances slowly by nature. Patients must remember what they ate several weeks ago.

Genomic tests to detect this parasite are particularly complicated to perform. Additionally, some health surveillance systems suffered drastic budget cuts recently. In 2025, the CDC reduced one of its main food monitoring systems.

The FoodNet system, once robust, now only tracks salmonella and one strain of E. coli. The remaining pathogens, including Cyclospora, were left as optional monitoring. This weakened early detection capacity across the country.

Experts Question Surveillance Cuts

Dr. Robert Redfield, former CDC director, openly criticized these budget reductions. “I don’t think it’s in our country’s interest to cut these programs”, he told CNN. He insisted that surveillance is fundamental for early outbreak detection.

The Department of Health and Human Services, however, defended its handling of the situation. Its spokesperson, Emily Hilliard, assured that the CDC continues collecting data on Cyclospora. She explained that they do so through systems other than FoodNet.

Hilliard also clarified that state funding for foodborne illnesses remained stable. She noted that approximately 33 million dollars are allocated annually for these activities. The FDA and CDC, she added, actively collaborate with state partners.

Why Cyclospora Is So Difficult to Trace

Unlike other pathogens, Cyclospora presents particular genetic complications. Bacteria like E. coli or salmonella allow for simpler genetic tracing. Their genetic information changes very little when transmitted between people or foods.

Jennifer McEntire, microbiologist and director of Food Safety Strategies, explained this difference clearly. She compared bacterial tracing to reading a simple children’s book. She defined Cyclospora, in contrast, as reading “War and Peace” in full.

This disease does not typically transmit directly between people in the usual way. People become infected by consuming contaminated food or water weeks earlier. Michigan ruled out, for now, any link to recreational water activities.

Prolonged Symptoms and Complicated Diagnosis

Those who contract cyclosporiasis can suffer symptoms for entire weeks. Watery diarrhea, cramps, and abdominal bloating are the most common. In severe cases, dehydration may require immediate hospitalization.

Standard treatment combines antibiotics for seven to ten consecutive days. Commercially known medications such as Bactrim or Septra are used. Many patients, however, never consult a doctor out of embarrassment.

Diagnosing the disease also represents a considerable technical challenge. The parasite is eliminated intermittently in the patient’s stool. For this reason, multiple tests are often needed to confirm the definitive diagnosis.

An Exhaustive and Thorough Investigation

Michigan warned that completing the investigation will take considerable time. The size of the outbreak and the complexity of food distribution complicate the process. Currently, more than 1,000 interviews have been conducted out of a total of 2,600 cases.

Bagdasarian detailed the effort behind each interview conducted. Her team reviews restaurant receipts, customer cards, and digital records. “Imagine the enormous amount of effort this entails”, the official explained.

Some restaurants voluntarily removed certain fresh ingredients from their menus. Authorities recommend buying whole lettuces instead of pre-washed ones. They also advise discarding the outer layers and thoroughly washing the inner leaves.