Here’s something you don’t see everyday: Local health officials are warning Americans to be on the lookout for cyclosporiasis, a parasitic infection that causes “explosive” diarrhea—yes, we said it—and has sickened nearly 700 people in the at least two U.S. states, with a majority of those cases in Michigan.

As of Monday, July 6, 678 cases have been confirmed in the Wolverine State— including in and around Detroit—according to the Michigan Department of Health and Human Services (MDHHS) as reported by ABC News, with one expert calling that number a “moving target” and likely to go up. (Typically, Michigan has 50 cases over the course of an entire year.)The remaining 177 cases were reported across Ohio (as of July 2), Ohio’s Department of Health told ABC.

Cases of cyclosporiasis have been increasing in multiple states since May, according to the U.S. Centers for Disease Control and Prevention. Previous to this most recent outbreak in the Midwest, 145 cases were reported in 17 states from May 1 to June 16 with the majority of cases in New York, Texas and Illinois. At least 20 people have been hospitalized but no deaths have been reported, per the CDC.

The parasite that causes cyclosporiasis—an intestinal illness—spreads through contaminated food or water that may contain feces, according to the CDC. It is not usually life-threatening.

Signs and symptoms of cyclosporiasis

The CDC says Cyclospora infects the small intestine (bowel) often resulting in “watery diarrhea” with frequent, and sometimes, “explosive bowel movements.” Those symptoms also include:

• Loss of appetite
• Weight loss
• Cramping
• Bloating
• Increased gas
• Nausea
• Fatigue

Less common symptoms may include:

• Vomiting
• Body aches
• Headache
• Low-grade fever
• Other flu-like symptoms

If not treated, illness may last from a few days to over four weeks, with some symptoms such as diarrhea, fading and, often relapsing; but other symptoms like fatigue lingering after gastrointestinal symptoms are over.

Symptoms can vary but usually begin about one week after becoming infected. See a healthcare provider if you are experiencing symptoms of cyclosporiasis.