Cyclospora is a microscopic parasite, known scientifically as Cyclospora cayetanensis, that infects the intestines and causes an illness called cyclosporiasis. People become infected after consuming food or water contaminated with the parasite, most commonly fresh produce such as leafy greens, herbs, and berries. The parasite must spend time in the environment before it becomes infectious, which means contaminated food and water are the primary routes of transmission. How Long Before Cyclospora Symptoms Appear? By the time symptoms appear, the contaminated food may have already been consumed, discarded or removed from store shelves.