Federal health officials have identified a new cyclospora outbreak stemming from an unspecified product, the U.S. Food and Drug Administration said Thursday. The FDA said the source of the outbreak was “not yet identified.”

A spokesperson for the agency told CBS News that the FDA had initiated a traceback, which is when investigators follow the path of a potentially contaminated food product through the supply chain in an effort to identify the origins of a foodborne illness outbreak.

“This is an active investigation,” the spokesperson said. “We will provide updates as they become available.”

It comes as health officials in North Carolina say they are investigating more than 560 cases there since May 1 that are possibly linked to parsley, cilantro and lettuce.

The FDA has opened investigations into multiple cyclospora outbreaks around the country, including one linked to iceberg lettuce from Taylor Farms that’s been blamed for thousands of illnesses in nine states including Michigan, Ohio, Indiana and Kentucky. 

That investigation led Taylor Farms to voluntarily recall all of its iceberg lettuce sourced from central Mexico.

A separate outbreak has resulted in at least 10 cases, the FDA said, while yet another outbreak has ended but remains under investigation. 

Cyclospora is a microscopic parasite that typically infects people through contaminated food or water. It causes a gastrointestinal illness called cyclosporiasis, which can result in symptoms like severe and sometimes “explosive” diarrhea. 

Cooking can kill the parasite, but health officials say just washing fruits and vegetables is not enough.

The Centers for Disease Control and Prevention says it has received reports of 4,173 lab-confirmed domestic cases of cyclosporiasis since May 1, and is and is aware of more than 7,400 additional cases that require further analysis to confirm.

So far the CDC has confirmed 1,947 illnesses linked to the iceberg lettuce-related outbreak from June 22 through July 20. 

However, state health departments in affected areas have tallied much higher numbers. Michigan health officials said Thursday that there are 7,664 confirmed cases of cyclosporiasis in that state alone, CBS News Detroit reported.

“Because cyclosporiasis is often underdiagnosed and underreported, the true number of illnesses is likely higher than what has been reported,” the CDC noted.