“Lettuce or salad greens” identified as a potential source of the Cyclospora outbreak
In a news release issued Monday, health officials in Michigan identified a possible cause of an outbreak of cyclosporiasis, a disease that results from infection with the parasite Cyclospora and is transmitted through food and water contaminated with feces.
“Current findings suggest that lettuce or lettuce leaves are a potential source for this outbreak,” officials said in the news release, but cautioned that the source is not yet definitive and other foods cannot be ruled out. They also didn’t specify a breeder or supplier.
As of Monday evening, health officials in Michigan had reported 2,640 cases and 44 hospitalizations — a 69 percent increase in cases from cases reported Friday and the highest number of cases ever reported in Michigan in a single year. The state typically only records 40 to 50 cases per year.
While Michigan is currently reporting the most Cyclospora infections in the country, the Centers for Disease Control and Prevention has said that many other states – including New York, Ohio, Illinois, Indiana and Kentucky – are reporting higher than average numbers of Cyclospora cases. The latest numbers from the CDC include at least 843 confirmed cases in 31 states and 86 hospitalizations.
Health experts say the CDC numbers are most likely an undercount because it takes time for states to report cases to the agency and for it to confirm them. The New York Times has independently confirmed at least 4,800 cases of Cyclospora so far this year. Since 2016, the CDC has reported an average of about 2,800 cases per year nationwide.
This year is “on track to be the biggest year ever for cyclosporiasis in the United States,” said Caitlin Rivers, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health who is tracking the cases.
Lettuce and salad mixes, as well as other types of fresh produce, including raspberries, basil, cilantro, fruit mixes, snap peas, and snap peas, have been implicated in previous Cyclospora outbreaks in the United States. A 2020 outbreak linked to Fresh Express packaged salads containing iceberg lettuce, red cabbage and carrots – the largest in recent history in the United States, according to the CDC – sickened 701 people in 14 states. The CDC also linked an outbreak in Florida in 2022 to packaged salads, including Caesar salad kits containing romaine lettuce.
Given the past association with lettuce and leafy greens and early indications that they may cause illness in Michigan, health officials there have issued specific guidelines for preparing the leafy greens. Instead of buying packaged or pre-mixed lettuce packets, they recommended using whole heads of lettuce, discarding the outer two to three layers of leaves, and then washing the inner leaves thoroughly under running water.
They also recommended washing other fresh produce under running water. Washing will not completely remove the parasite, but it can reduce its numbers and the risk of disease. Health officials have also recommended peeling produce with removable shells and cooking produce at at least 158 degrees, a temperature that kills the parasite.
Cyclospora infections cause watery diarrhea with frequent, sometimes “explosive” stools. Other symptoms may include loss of appetite, cramps, bloating, nausea and fatigue. Although serious complications are rare, symptoms can last for several months without treatment.
People with symptoms should see a doctor for testing and treatment for the disease, the CDC said Friday. Cyclosporiasis can be treated with antibiotics.
