Parasite cyclospora spreads through produce and water contaminated with feces and causes the intestinal illness cyclosporiasis The US Centers for Disease Prevention has been working to find the source of a parasitic illness that causes “explosive”, watery diarrhea, with more than 400 cases of the sickness reported across 18 states. The parasite, cyclospora, spreads through raw produce and water contaminated with human feces – and it causes the intestinal illness cyclosporiasis, whose symptoms include cramps, nausea, fatigue, loss of appetite, low-grade fever and vomiting. The most commonly reported symptom is “watery diarrhea with frequent and sometimes explosive bowel movements”, according to the CDC .