FDA Investigates Lettuce and Other Produce as Massive Parasite Outbreak Spreads Across 34 U.S. State

BY MIRABEL ODETA

U.S. health officials are racing to identify the source of one of the country’s largest foodborne illness outbreaks in recent years after a widespread surge in cyclosporiasis infections sickened thousands of people across dozens of states. The U.S. Food and Drug Administration (FDA) confirmed that it is investigating multiple fresh produce items, including lettuce, as part of an ongoing effort to determine what triggered the unusually large outbreak.

According to the latest data from the U.S. Centers for Disease Control and Prevention (CDC), laboratory testing has confirmed 1,645 cases of cyclosporiasis across 34 states since May. The outbreak has already resulted in 141 hospitalizations, although no deaths have been reported. Health officials also revealed that more than 5,100 additional reported illnesses are still undergoing analysis and laboratory confirmation, meaning the total number of infections could increase significantly in the coming weeks.

Cyclosporiasis is an intestinal illness caused by the parasite Cyclospora cayetanensis. The infection commonly spreads through contaminated food or water, particularly raw fruits and vegetables that have come into contact with human waste. Symptoms usually include prolonged diarrhea, stomach cramps, nausea, vomiting, fatigue, loss of appetite, bloating, and weight loss. While many patients recover with proper treatment, the illness can become severe or prolonged if left untreated, especially among individuals with weakened immune systems.

Health authorities say the scale and geographic spread of this year’s outbreak are far greater than those seen in previous years. Although the United States has experienced cyclosporiasis outbreaks before, investigators have not yet identified a single food item or supplier responsible for the current surge, making the investigation more complex.

The FDA has launched extensive traceback investigations to determine where contaminated produce may have entered the food supply. Investigators are interviewing infected individuals to learn what foods they consumed before becoming sick and are tracking supply chains from grocery stores and restaurants back to farms and distributors.

Lettuce is among the produce items currently under investigation, although federal officials emphasized that no specific product has been confirmed as the source. Acting FDA Deputy Commissioner for Food Donald Prater said investigators are examining several possible food items and stressed that there is currently no evidence requiring consumers to avoid any particular fruit or vegetable.

Reports have also drawn attention to Taco Bell after officials examined whether lettuce served at some of the restaurant chain’s locations could be linked to the outbreak. The company stated that it voluntarily removed certain ingredients from select restaurants as a precaution while the investigation continues. However, Taco Bell also emphasized that U.S. health authorities have not established any direct connection between its restaurants and the outbreak.

The CDC has issued an alert urging healthcare providers to consider testing patients showing symptoms consistent with cyclosporiasis. Officials say early diagnosis is essential because many cases can go undetected if healthcare professionals do not specifically test for the parasite.

Some public health experts have criticized the pace of the federal response, arguing that quicker identification of contaminated food could help prevent additional infections. Infectious disease specialist Dr. Michael Osterholm of the University of Minnesota said stronger coordination and clearer communication from both federal and state agencies are needed during large-scale foodborne illness investigations.

Minnesota Senator Amy Klobuchar has also called for restoring funding and staffing for federal and state food safety programs, arguing that stronger oversight and greater resources are necessary to improve outbreak detection, food inspections, and emergency response efforts.

The CDC expects the number of confirmed infections to continue rising through the end of August. Officials explained that there is typically a delay of about six weeks between the onset of symptoms and the confirmation of reported cases due to laboratory testing and public health investigations. As a result, many additional infections may still be identified even if the original source of contamination is no longer present in the food supply.

Michigan has emerged as the hardest-hit state, reporting 3,309 cases so far. Ohio and New York have also recorded significant numbers of infections, while cases have been confirmed in dozens of other states nationwide.

Investigators believe that infections reported in Michigan, Ohio, Kentucky, and West Virginia may be connected to a common source, although this potential link does not explain cases reported elsewhere. Public health officials continue to investigate several additional clusters, including outbreaks limited to individual states and isolated cases that currently cannot be connected to any known source.

Experts note that tracing foodborne outbreaks involving fresh produce presents unique challenges because fruits and vegetables often have short shelf lives and move rapidly through complex distribution networks before reaching consumers. By the time illnesses are reported and investigated, the contaminated products have often already been consumed or discarded, making it difficult to collect evidence.

Despite these challenges, the FDA says investigators are examining multiple clusters and supply chains simultaneously in an effort to determine whether the outbreak originated from a single contaminated source or several unrelated incidents. Officials also cautioned that it remains too early to conclude whether the outbreak has ended, as new reports continue to emerge from across the country.

The investigation remains active, and health authorities say they will continue monitoring new cases while working with state health departments, laboratories, food distributors, and agricultural producers to identify the source and prevent further infections.