A gut-busting parasite that’s known to cause “weeks of debilitating diarrhea” is spreading across the United States — and investigators are racing to understand what’s behind recent outbreaks.
The intestinal infection, called cyclosporiasis, is caused by the microscopic parasite Cyclospora cayetanensis, and is known to cause frequent — and often explosive — watery diarrhea. The foodborne pathogen is typically linked to imported fresh produce, according to the Centers for Disease Control and Prevention, and spreads when people ingest food or water that was contaminated with feces.
The official data is a bit of a mess as of right now. The CDC’s official tally — just 145 cases across 17 states — hasn’t been updated since June 16, but state-level data suggests that the outbreak is growing rapidly. As CNN reports, Michigan alone has reported a whopping 681 cases since June 22; the vast majority of the 177 cases reported in Ohio occurred since June 20, while New York state has identified more than 100 in the last three weeks, without even counting New York City, which has seen some cases as well.
It’s hard to imagine that the cases aren’t connected, but we don’t even know that for sure. Investigators are desperately trying to find the source, but early indications suggest there may be several.

