Got a nasty stomach bug that won’t go away? It could be cyclosporiasis, a parasitic infection that causes weeks of debilitating diarrhea, cramps and bloating.

This infection tends to occur during the warm summer months, but several states are reporting increases in cases beyond what they would normally expect at this point in the year.

Michigan, which says it typically logs about 50 cases of cyclosporiasis annually, says it has seen 681 since June 22, pointing to an outbreak with a common source. Several nearby states are also seeing unusual upticks.

Since the beginning of the year, Ohio says, it has received reports of 177 cyclosporiasis cases, with 171 of those coming in June, mostly since June 20.

New York state says it’s seen 112 cases this year – outside of New York City – with 107 of those reported since May 1.