The Food and Drug Administration is investigating the cyclospora infections, which are most often found in tropical or subtropical countries and have been linked to imported fresh produce in the past.
The illness is usually spread when people ingest foods or water contaminated with feces. The agency said it isn't yet clear whether the cases from all of the states are linked.
The number of reported illnesses expanded from more than 200 to more than 250 on Tuesday, according to the CDC. The CDC added Georgia and Connecticut to the list of affected states.
The agency said it is investigating additional illnesses and the number of those sickened could grow.