The largest cyclospora outbreak ever recorded in the United States has infected more than 22,000 people and been linked to two deaths in Michigan, with public health researchers pointing to sewage contamination of the food supply as the likely cause. Cyclospora (an intestinal parasite that causes severe diarrhea and exists only in humans) spreads when oocysts shed in human feces survive standard wastewater treatment and re-enter the environment through irrigation water used on crops — a cycle made harder to break because common disinfection methods such as chlorination do not kill the organism. Experts warn that expanding wastewater surveillance and adopting more effective treatment technologies such as ultraviolet disinfection are urgently needed, particularly as climate-related floods, droughts, and rising temperatures increase the risk of contaminated water reaching food supplies.