NEW YORK — Parasitic illness cases in 15 states have been linked to iceberg lettuce, U.S. health officials said Wednesday. Cyclospora cases have been reported in at least 47 states this year, and investigators have continued to probe how many could be linked to a common contaminated source. The Centers for Disease Control and Prevention said the number of states tied to the deadly outbreak had grown from nine to 15. Federal officials subsequently said they are focused on Taylor Farms as the source of the lettuce in the outbreak, and the company has recalled iceberg lettuce grown in central Mexico. Adding in the other states that have reported cases, the national total stands at over 25,000.