Hundreds of people across at least 17 states have been infected with cyclosporiasis, an intestinal illness caused by the Cyclospora parasite, with investigations underway to identify the source of the contamination, which is suspected to be fresh produce.
Michigan has been particularly affected, reporting over 700 cases, according to Dr. Natasha Bagdasarian, Michigan's chief medical executive. The state's health department was alerted to a potential widespread outbreak in early July, a significant increase from the typical 40 to 50 cases seen annually. While many cases of cyclosporiasis in the U.S. typically occur in individuals who have traveled abroad, the current outbreak involves people who have not left the country, leading health officials to conduct interviews about dietary habits and grocery purchases.
Cyclosporiasis is caused by the Cyclospora cayetanensis parasite, which can contaminate fresh produce and vegetables. The parasite spreads primarily through human feces, and inadequate sanitation in fields where produce is grown and harvested is considered a major source. Warm, damp conditions can also favor the parasite's growth, with some experts suggesting climate change may play a role.
Symptoms of cyclosporiasis include diarrhea, frequent and sometimes explosive bowel movements, and abdominal discomfort. Unlike some foodborne illnesses that cause vomiting and nausea, cyclosporiasis symptoms tend to be localized to the lower gastrointestinal tract and can persist for weeks. Some infected individuals may not exhibit any symptoms.
Diagnosing cyclosporiasis can be challenging, as it is relatively rare and not typically included in standard stool test panels. Doctors must specifically request a Cyclospora stain for detection. Due to the current outbreak, healthcare providers are likely more aware of the parasite and more inclined to order testing, especially for individuals with persistent diarrhea or those at higher risk of complications, such as young children and individuals with weakened immune systems.
While most cases resolve on their own, antibiotics can sometimes be used to shorten the duration of the illness for those at higher risk of complications.
Preventing cyclosporiasis involves careful handling and preparation of produce. The Cyclospora parasite is difficult to remove once produce is contaminated. Items with many crevices, such as raspberries, blackberries, lettuce, cilantro, green onions, and basil, are more prone to harboring the parasite. Cooking produce can kill the parasite. For fresh produce, washing thoroughly is recommended, with smoother fruits like grapes and blueberries being easier to clean effectively.
Federal agencies, including the U.S. Food and Drug Administration (FDA), are responsible for inspecting both domestic and imported food products. However, concerns have been raised about potential understaffing and underfunding of agencies like the FDA, which could impact their ability to prevent foodborne illnesses. The origin of the current outbreak, whether from domestically grown or imported food, remains unclear. Improving field sanitation and the quality of rinsing water used on produce after harvest are considered potential measures to reduce contamination risks.