US cyclospora outbreak spreads, source still unknown

A widespread outbreak of the foodborne illness cyclosporiasis has sickened thousands of people across the United States, presenting significant challenges for investigators attempting to trace the source of the microscopic parasite. As of July 20, federal officials have reported thousands of confirmed and suspected cases spanning dozens of states, with over a hundred hospitalizations.

Public health officials have linked a significant multistate outbreak affecting Michigan, Indiana, Kentucky, Ohio, and West Virginia to shredded iceberg lettuce served at Taco Bell restaurants. The lettuce was supplied by Taylor Farms, which has issued a voluntary recall of all iceberg lettuce products sourced from its operations in central Mexico. Despite this link, officials note that Taco Bell accounts for only a portion of the total national cases, indicating other potential sources and outbreaks are under investigation.

The investigation has been hampered by the unique characteristics of the cyclospora parasite. Unlike bacteria such as salmonella or E. coli, cyclospora cannot be cultured in a laboratory, preventing scientists from using whole genome sequencing to create a definitive genetic...