The CDC expanded the outbreak of cyclosporiasis linked to shredded iceberg lettuce to an additional four states, a CDC official told ABC News on Friday.

CDC confirms 4,173 U.S. Cyclospora cases as it investigates a lettuce-linked outbreak. More than 7,400 additional reports remain under review.

The FDA is investigating at least five other clusters of cyclosporiasis, including an outbreak of 72 cases reported by the agency on Wednesday.

Investigators believe additional states will help them better construct how cyclosporiasis moved through the nation's food supply.