Cyclospora outbreak linked to iceberg lettuce expands to 4 more states

A cyclospora outbreak linked to shredded iceberg lettuce from central Mexico has expanded to four more states, the U.S. Department of Health and Human Services confirmed to CBS News on Friday. This brings the total number of states affected to nine.

The newly linked states are Illinois, Kansas, Oklahoma and Pennsylvania. The outbreak was previously linked to Indiana, Kentucky, Michigan, Ohio and West Virginia. The expansion was first reported by the Washington Post.

Cyclospora is a microscopic parasite that typically infects people through contaminated food or water. It causes cyclosporiasis, a gastrointestinal illness that can result in symptoms including severe diarrhea. Patients can require hospitalization. 

The iceberg lettuce was linked to produce giant Taylor Farms. The company voluntarily recalled all of its iceberg lettuce sourced from central Mexico. Taylor Farms is a key supplier of lettuce and other produce to retailers including Walmart, Target and Whole Foods, and restaurant chains including Taco Bell. 

The outbreak was already the nation's largest. Thousands of cases have been reported this year, far exceeding the 200 to 1,000 cases that are usually reported.

A separate outbreak is also under investigation by the Food and Drug Administration from an unspecified product.

The Centers for Disease Control and Prevention says it has received reports of 4,173 lab-confirmed domestic cases of cyclosporiasis since May 1, and is and is aware of more than 7,400 additional cases that require further analysis to confirm. So far, the agency has confirmed 1,947 illnesses linked to the iceberg lettuce-related outbreak from June 22 through July 20. 

State health departments have recorded much higher numbers. Michigan health officials said Thursday that the state has confirmed 7,664 cases. 

Cyclosporiasis symptoms can take weeks to show up, making it difficult to trace.