Cyclospora cayetanensis is a microscopic, single-celled parasite that causes cyclosporiasis, an intestinal illness leading to watery diarrhea and other gastrointestinal symptoms. Understanding where this parasite is found in food, water, and various environments is fundamental for preventing infection and limiting its spread. Recognizing typical sources of contamination helps in identifying risks and implementing protective measures.
How Cyclospora Spreads to People
Transmission of Cyclospora cayetanensis to humans primarily occurs through the fecal-oral route, when individuals consume food or water contaminated with the parasite’s infectious stage. Fresh produce serves as a common vehicle for this contamination. Outbreaks in the United States have been linked to various raw fruits and vegetables, including:
- Raspberries
- Blackberries
- Basil
- Cilantro
- Leafy greens (mesclun, lettuce)
- Snow peas
- Broccoli
- Pre-packaged salad mixes
Contamination of produce often takes place during cultivation, harvesting, or processing, particularly in regions where sanitation practices are insufficient. The parasite’s oocysts can adhere to the surfaces of produce, making thorough cleaning challenging.
Water also plays a significant role in the spread of Cyclospora. Water sources can become contaminated with parasite oocysts from infected human feces. This includes drinking water, recreational water in pools or lakes, and especially water used for irrigation in agricultural settings. Produce grown or washed with untreated water is at a higher risk of contamination.
Global and Environmental Habitats
When Cyclospora oocysts are shed in the feces of an infected individual, they are initially unsporulated and not yet infectious. These oocysts must mature in the environment to become capable of causing infection. This maturation process, known as sporulation, requires specific environmental conditions, typically temperatures between 22°C and 32°C, and usually takes between 7 and 14 days.
Once sporulated, the oocysts are remarkably resilient and can survive for extended periods in various environmental matrices, persisting for months in both soil and water. Cyclospora oocysts are also resistant to many common disinfectants and sanitizers used in food processing and water treatment, making their elimination challenging.
Cyclospora is found globally, but it is particularly prevalent in tropical and subtropical regions. Outbreaks in non-endemic areas, such as the United States and Canada, are frequently traced back to imported fresh produce from these endemic regions, highlighting the impact of global food supply chains on the parasite’s spread.
Infected individuals play a role in the parasite’s environmental cycle by shedding oocysts in their feces. If proper sanitation and hygiene practices are lacking, these oocysts can contaminate surrounding environments, including water sources and agricultural fields. Direct person-to-person transmission of Cyclospora is unlikely because the oocysts need time in the environment to mature and become infectious after being shed.