Cyclosporiasis, an intestinal infection caused by the cyclospora parasite, is spreading at an unusually high rate across the United States this season.
The infection typically picks up during summer months, but health officials say this year’s outbreak is more severe than usual, with mysterious clusters emerging in several regions.
On July 14, the U.S. Centers for Disease Control and Prevention confirmed a large outbreak affecting four midwestern states, with Michigan recording over half of all national cases.
The Michigan Department of Health and Human Services reported 3,309 cyclosporiasis cases since June 22, a sharp jump from the 2,640 cases recorded just one day earlier on July 13.
Of those Michigan cases, 44 individuals had been hospitalized as of July 9, underscoring how serious the infection can become without prompt medical attention.
Early results from Michigan health officials point to lettuce or salad greens as a potential culprit in the state’s outbreak, though other foods have not yet been ruled out.
“If you get norovirus or something, you might have a rough 24 or 48 hours, but people with this parasite can be sick for weeks or sometimes even months with a sort of relapsing pattern, and so that can really wear down your body,” said Dr. Caitlin Rivers, an epidemiologist and senior scholar at the Johns Hopkins Center for Health Security.
Health officials recommend purchasing whole heads of lettuce rather than pre-washed, bagged lettuce or pre-mixed salad kits, which carry a higher contamination risk.
Consumers should discard the outer two to three layers of leaves and thoroughly wash the remaining inner leaves under clean running water before eating them.
Experts caution that “pre-washed” labeling does not guarantee safety, and rewashing bagged lettuce is unlikely to fully remove cyclospora from the surface of greens.
Cooking food to an internal temperature of 158 degrees Fahrenheit or higher kills cyclospora, according to the Michigan Department of Health and Human Services, making heat the most reliable protection.
Research suggests that soaking produce in a mixture of three parts water and one part vinegar for a few minutes can help remove the parasite, though it will not fully kill it.
Raspberries are considered especially high-risk because their bumpy surface creates tiny crevices where the parasite can hide, making them very difficult to clean effectively.
To date, no commercially frozen produce, cooked foods, or peeled fruit have been associated with cyclosporiasis infection, making those options considerably safer during the current outbreak.
People experiencing frequent, watery diarrhea should contact their healthcare provider and specifically request testing for cyclospora, since routine stool tests may miss the parasite entirely.
Cyclosporiasis is treated with antibiotics combined with rest and adequate fluid intake to prevent dehydration during what can be a prolonged and physically draining illness.
