On Wednesday, the CDC increased its count of cyclosporiasis cases in the United States, confirming more than 4,100 infections in 41 states since May.

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

As cases of cyclosporiasis are continuing to increase across the U.S., here's what we still don't know about a multi-state outbreak.