The nationwide cyclospora outbreak is very likely a result of sewage contamination in the food supply, according to scientific researchers and public health officials.
The parasite’s spread can become a self-perpetuating cycle. Cyclospora is found only in humans, where it replicates in the intestinal tract, causing severe diarrhea. The organism reproduces by releasing oocysts, which are excreted in those human feces. In the U.S., feces usually end up in sewage systems.
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. The oocysts mature in the environment with warm temperatures in about a week. Then a human comes along and eats the irrigated food or drinks the water and gets sick, releasing more oocysts into sewage systems.
I am a public health water microbiologist who collects sewage water and tests it for evidence of harmful pathogens, such as cyclospora. The first time I studied cyclospora was in the first outbreak ever documented in the U.S., a small, 45-case outbreak in Florida in 1995.
