US sees surge in cyclosporiasis cases, officials investigate produce links
Health officials report a sharp rise in cyclospora infections across more than 30 states, with Michigan accounting for the majority of cases, and are examining lettuce and other produce as possible sources.
Health authorities have reported a significant increase in cyclosporiasis, an intestinal infection caused by the Cyclospora cayetanensis parasite, with about 5,000 cases confirmed in over 30 states as of mid-July. Michigan alone accounts for roughly 3,300 cases, making it the hardest-hit state, while Ohio, New York, North Carolina and Illinois have each reported hundreds of infections.
The parasite spreads when people consume food or water contaminated with fecal matter containing the organism. Experts note that the parasite requires one to two weeks outside the body to become infectious, which limits person-to-person transmission. Symptoms typically include sudden, watery diarrhea that can persist for weeks, though the illness is rarely life-threatening and responds well to a specific antibiotic regimen.
Michigan health officials have identified lettuce or salad greens as a potential source in the state’s outbreak but cautioned that other foods have not been ruled out. The Centers for Disease Control and Prevention said there is no evidence of a single, nationwide source and that multiple, unrelated outbreaks may be occurring simultaneously. Some researchers suggest that water used for irrigation, particularly in counties bordering Lake Erie, could also play a role.
"The very quick uptick and high numbers of cases, I would say, is unusual," said Kali Kniel, Ph.D., a professor of microbial food safety at the University of Delaware.
"There may be multiple unrelated outbreaks going on at the same time," said Donald Schaffner, Ph.D., a food microbiology professor at Rutgers University.
"Much more likely, there are multiple parallel pathways for people to become infected," said Dr. Trevor Suslow, a food-safety expert at the University of California, Davis.
Because no definitive source has been identified, officials advise against avoiding fresh produce altogether. Instead, they recommend standard safety practices such as washing hands with soap, scrubbing fruits and vegetables under running water, removing outer leaves of lettuce, and cooking greens to at least 158 °F (70 °C) when possible. Freezing can reduce risk, though it is not guaranteed to eliminate the parasite.
People with weakened immune systems are urged to consult healthcare providers for additional precautions. Those who develop symptoms should seek medical attention, as treatment is effective and hydration is important.
State health departments continue to monitor the situation and work with the CDC and the Food and Drug Administration to identify any common sources and to issue further guidance as needed.