The outbreak of infections caused by a parasite may stem from contaminated lettuce, officials in Michigan, where most of the cases are, said on July 13.
“While the investigation is ongoing, current results point to lettuce or salad greens as a potential source for this outbreak, although other food items cannot be completely ruled out,” the Michigan Department of Health and Human Services said in a statement.
“No specific type of produce, grower or supplier has been identified as the source.”
Cyclospora, a parasite that spreads through produce contaminated with feces, has been causing cyclosporiasis infections across the country. More than half of the 50 states have reported at least one case, the Centers for Disease Control and Prevention said. In Michigan, cases soared to 2,640 as of Monday.
Cyclosporiasis cases happen each year in the United States, but the number of cases is typically much lower. Michigan only records 40 to 50 cases in a normal year.
Prior outbreaks have been caused by contaminated romaine lettuce, raspberries, bagged salad mix, cilantro, scallions, and sugar snap peas.
Federal and state officials say they have been investigating the cause of the current outbreak. The possible link to lettuce or salad greens is the first time any officials have designated a potential source.
“Although we do not have a definite product identified as the source of the outbreak, we want to let Michiganders know what we have learned so far so they can take steps to protect their families,” Dr. Natasha Bagdasarian, chief medical executive of Michigan’s health department, said in a statement.
“Early information has shown lettuce as a common product that regularly comes up during the investigation. We will continue to provide updates as we learn more.”
The Department of Health and Human Services, the CDC’s parent agency, said on X on Monday that the CDC is working with 3,000 health departments across the country to gather data on the outbreak and that the Food and Drug Administration is investigating alongside the CDC and state and local partners “using established epidemiologic, laboratory, and traceback tools.”
The cyclospora parasite infects one’s intestines and causes symptoms such as watery diarrhea, nausea, and stomach cramps.
Michigan officials are advising people to avoid bagged lettuce and salad mixes and instead purchase whole heads of lettuce. People should discard the two or three outer layers of leaves and thoroughly wash the inner leaves, they said.
Any greens that should be cooked should be done to at least 158 degrees Fahrenheit, because cyclospora is resistant to chemical disinfection and “washing alone cannot guarantee its removal,” the Michigan Department of Health and Human Services said. For other produce, peeling and cooking are recommended.