A microscopic parasite is behind a summer wave of “explosive” diarrhea spreading across the United States. Health officials are tracking a sharp rise in cases, and while it sounds alarming, the illness is usually treatable and rarely dangerous.

Cases of cyclosporiasis, a parasitic foodborne illness that can cause "explosive" diarrhea, are being reported across the United States, including in Rhode Island.

Cyclosporiasis can lead to “explosive” and watery diarrhea in some patients, but no symptoms in others, according to the CDC.