Federal health authorities say more than 275 people in seven states have now been sickened with an unidentified stomach bug.

The Food and Drug Administration is investigating the cyclospora infections, which are often found in tropical or subtropical countries and have been linked to imported fresh produce in the past. It causes diarrhea and other flu-like symptoms.

The Centers for Disease Control and Prevention says the infection has been reported in Iowa, Nebraska, Texas, Wisconsin, Georgia, Connecticut and New Jersey. Most of the illnesses occurred from mid-June to early July. The CDC says it isn't clear whether the cases are all linked.

The illness is spread when people ingest foods or water contaminated with feces. The agency said it isn't clear whether the cases are all linked.