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.

“There is currently no evidence of a single, multi-state Cyclospora outbreak linking all cases,” the CDC notes on its website. “Investigations to identify potential clusters and potential sources of illness are ongoing.”

“At this time, no specific produce grower, supplier, or type of produce has been identified as the source,” Michigan Department of Health and Human Services (MDHHS) spokesperson Laina Stebbins told the Detroit Free Press. “Anyone experiencing gastrointestinal illness, such as sudden and ongoing diarrhea, should contact their health care provider and their local health department.”

Tracking down the nasty bug isn’t straightforward as males and females of the parasite swap parts of their DNA to reproduce, meaning their offspring often have different genes. Epidemiologists are stuck painstakingly interviewing those suffering from the illness to see what they ate and when.

Conventional lab tests for pathogens don’t show the presence of Cyclospora, making it tricky for health officials to trace outbreaks. Eggs of the parasite need to be colored with a special dye and identified under a microscope to confirm infection.

While explosive diarrhea for anywhere from a couple of days to a month sounds exceptionally unpleasant, the situation could be a lot worse. For one, there are treatments available and people eventually recover from the illness. Person-to-person transmission is also unlikely as it takes the pathogen one to two weeks to become infectious outside of the body, per the CDC.

To protect yourself from suffering such an unfortunate fate, health officials are recommending being extra careful about the preparation of fresh produce. The MDHHS advises people to stay away from pre-washed, bagged lettuce, throw away the outer leaves of whole heads of lettuce, and spend time carefully washing green vegetables and herbs under running water.

To be extra safe, people are encouraged to heat or cook their food to at least 158 degrees Fahrenheit, which will kill the parasite — advice which would surely result in some avant-garde salads.

According to the CNN, previous outbreaks of the diarrhea parasite were traced back to raspberries, basil, salad mixes, berries, and snap peas.

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