Cyclospora Infections Surge in the U.S.: Health Officials Investigate

Health officials are currently investigating an increase in cyclospora infection, a foodborne illness characterized by intense diarrhea, spreading across the United States. Reports of outbreaks have emerged from several states, with Michigan experiencing an unusually high number of cases.

Understanding Cyclosporiasis

Cyclosporiasis results from the microscopic parasite Cyclospora cayetanensis. According to the Centers for Disease Control and Prevention (CDC), this illness often causes watery diarrhea, which can become explosive. In previous U.S. outbreaks, contaminated fresh produce was often found responsible, with infections worsening in summer months.

State Reports on Case Rise

Recent CDC surveillance data and state health department reports show confirmed cases in at least the following states:

• Alaska
• Colorado
• Connecticut
• Florida
• Georgia
• Illinois
• Louisiana
• Massachusetts
• Michigan
• New Jersey
• New York
• North Carolina
• Ohio
• Pennsylvania
• Tennessee
• Texas
• Virginia
• Wisconsin

Michigan has registered the most confirmed cases, while Ohio has noted significant increases. Other states are investigating smaller clusters.

Michigan’s Unusual Outbreak

Michigan has experienced over 700 confirmed cases, a number described by state officials as highly unusual. Authorities are analyzing food histories and grocery purchases to trace potential contamination sources. As of early July, Ohio reported 177 cases and Texas noted 48 cases. New York, North Carolina, and Illinois have also reported increased or suspected cluster cases.

CDC Observations

Per the CDC, cyclosporiasis cases generally increase between May 1 and August 31. The CDC’s latest national surveillance data, covering May 1 to June 16, detailed 145 domestically acquired cases across 17 states, including 20 hospitalizations and no fatalities. Although the surveillance data publishes after a delay, public state case counts suggest the actual infection number is much higher.

The CDC’s investigation indicates no evidence of a singular nationwide outbreak, so federal and state investigators continue examining multiple clusters for common food sources.

Official Reports and Undercounting

Public health officials note reported case counts are likely lower than actual infections because not all infected individuals undergo laboratory testing or medical care. Delays between exposure, symptom onset, testing, and reporting mean surveillance data often lag behind real-world outbreaks.

Foods Linked to Previous Outbreaks

While investigators have not yet identified the specific source behind the current outbreaks, past U.S. outbreaks linked to cyclospora have involved:

• Basil
• Cilantro
• Mesclun lettuce
• Bagged salad mixes
• Raspberries
• Snow peas
• Green onions (scallions)

Fresh produce is often implicated because contamination can occur when irrigation water or environmental factors affect the foods before reaching consumers.

Symptoms to Watch

Symptoms typically begin about a week after ingesting contaminated food or water, though they can appear between two days and two weeks later. Common symptoms include:

• Watery diarrhea
• Severe diarrhea
• Stomach cramps
• Bloating
• Nausea
• Loss of appetite
• Fatigue
• Weight loss

Without treatment, these symptoms may persist for several weeks, occasionally improving before returning.

Continued Investigation

The Food and Drug Administration, CDC, and state health departments are actively probing potential contamination sources. As of now, no specific grower, supplier, or food product has been identified. Due to seasonal patterns and reporting delays, additional cases are expected in the coming weeks. Investigators are working to determine whether multiple, unrelated contamination events might be causing the current illnesses, as opposed to one large outbreak.