India, July 14 -- Health officials are investigating whether lettuce or salad greens may be linked to a growing Cyclospora outbreak, but no specific food item, supplier or grower has been identified as the source.

A Cyclospora outbreak that has sickened more than 3,000 people in Michigan and Ohio is being investigated for a possible link to lettuce and other salad greens, health officials said.

Michigan officials said early findings from their investigation showed lettuce was a common product reported by people who developed infections. However, authorities stressed that the investigation is still ongoing and other foods cannot be ruled out.

"Early information has shown lettuce as a common product that regularly comes up during the inv...