In many states, sewage water is treated – though not always in ways that remove or kill the oocysts – and then released into waterways and can be used to irrigate crops. It is not easy to measure cyclospora oocysts in sewage, contaminated water or food. Based on what is known about other fecal pathogen excretions from patients, related to the concentrations of those pathogens in sewage, I estimate that there could be anywhere from 1 to 100 oocysts per liter in sewage.