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What is cyclosporiasis? ‘Explosive’ parasitic infection outbreak spreading across US; Check symptoms, treatment, map
Cyclospora infections, primarily linked to contaminated food, have increased notably this summer, especially in Michigan.
A parasite that induces explosive diarrhea is responsible for a rise in summer food poisoning incidents just ahead of Independence Day.
Cyclosporiasis, a distressing illness triggered by a parasite commonly present on fruits and vegetables, has affected hundreds of individuals in over 17 U.S. states since May 1, as reported by the Centers for Disease Control and Prevention (CDC) along with state health statistics. Michigan, in particular, is facing a significant outbreak of infections that has already more than tripled its total case count in comparison to 2025.
Medical professionals informed ABC News that cases typically begin in May, stating that the outbreak in Michigan coincided with the period when public health experts generally anticipate an increase in cases. However, physicians noted that the incidence of cases in Michigan is notably elevated.
Dr. Peter Chin-Hong, an expert in infectious diseases and associate dean for regional campuses at the University of California, San Francisco, conveyed to ABC News that in previous years, the United States often experienced numerous cases of cyclosporiasis contracted from outside the country, particularly from imported fruits and vegetables.
Here's what CDC and FDA are doing
State health authorities, along with the CDC and the Food and Drug Administration (FDA), are currently investigating to find a common link among the illnesses; however, no singular outbreak has been pinpointed. Rather, the cases observed so far seem to be part of a seasonal increase, although officials are actively looking for a possible connection.
"CDC has no evidence of a single, multistate Cyclospora outbreak linking cases happening right now and being reported in press," the agency stated in a June 2 statement to USA TODAY. “The data currently found on CDC’s website is a surveillance count of cases across the United States of people with cyclosporiasis. This number includes clusters of cases currently under investigation by FDA and cases that have not been linked to a common source.”
What is Cyclosporiasis? Here are symptoms
Cyclosporiasis is a parasitic infection that leads to uncomfortable gastrointestinal symptoms typically linked to food poisoning, including diarrhea, nausea, and vomiting. This condition is caused by the parasite Cyclospora cayetanensis, commonly referred to as cyclospora, and is primarily acquired through the consumption of contaminated food.
The predominant symptom is watery, frequent, and at times "explosive" diarrhea, as noted by the CDC and Cleveland Clinic. Other gastrointestinal issues may encompass: loss of appetite, bloating, which may involve burping and gas, or abdominal cramps, severe fatigue, fever, nausea and vomiting.
Tracking of cyclosporiasis cases
CDC's tracking of cyclosporiasis cases is based on the location of infection.
On June 16, a total of 145 people across 17 states have reported contracting the infection after consuming food within the United States. Additionally, 45 people, who are monitored and classified separately, have contracted the infection while traveling internationally.
Among the 145 people who fell ill in the US states, 20 were admitted to hospitals, and fortunately, there were no fatalities. The cases were reported in individuals ranging in age from 5 to 86, with a median age of 42. According to the CDC, the "cyclosporiasis season," which is the period when the U.S. generally experiences an increase in cases, commences on May 1 and continues until the end of August.
However, these figures do not account for the over 150 people who have reported illness in Michigan following the identification of the first case in the state on June 22. As of July 1, the state's health department indicated that "more than 170 cases" had been documented, marking a notable increase from the approximately 50 cases reported statewide last year.
In a statement to USA TODAY on July 2, the CDC mentioned that it did not have any new data to share and that the surveillance dashboard for cyclosporiasis infections is updated on a monthly basis. The map below illustrates the most recent CDC data available as of June 16, along with additional state-level reporting as of June 30.
Cases of cyclosporiasis reported in the U.S. include:
Alaska
Colorado
New Jersey
New York
North Carolina
Ohio
Pennsylvania
Florida
Georgia
Illinois
Louisiana
Massachusetts
Michigan
Tennessee
Texas
Virginia
Wisconsin
Connecticut
Cyclosporiasis: Know about treatment
Cyclosporiasis is managed with the oral antibiotic trimethoprim-sulfamethoxazole (TMP-SMX), which is commonly marketed under the names Bactrim, Septra, and Cotrim, and is administered for a duration of 10 days, as stated by the CDC.
Dr. Zoe Weiss, who serves as the director of clinical microbiology at Tufts Medical Center, shared this information with ABC News.
Medical professionals informed ABC News that people can reduce their risk of infection by thoroughly washing fruits and vegetables, removing any bruised or damaged sections, and storing pre-prepared or pre-cut produce in the refrigerator.
"If you're in an area that's been affected and you have sudden ongoing watery diarrhea, you should definitely seek a physician and get treatment," Dr. Zoe Weiss, director of clinical microbiology at Tufts Medical Center, told ABC News.
