The US Food and Drug Administration has widened its investigation into a Cyclospora outbreak, adding six more states to bring the total to 15, as confirmed cases surpassed 6,000. The illness was first identified in July among people who developed severe diarrhoea after eating shredded lettuce at Taco Bell, with health officials subsequently tracing contamination to iceberg lettuce supplied by Taylor Farms de Mexico. The expanding scale of the investigation underscores the difficulty of pinpointing and containing a foodborne outbreak once contaminated produce has entered a wide supply chain.

The FDA said that additional interview data had broadened the case definition to include anyone who reported exposure to Taco Bell or to recalled Taylor Farms de Mexico iceberg lettuce, which explains the sharp rise in confirmed infections to 6,358. Separately, Michigan has reported two deaths linked to the wider parasite outbreak, which health authorities say has now sickened more than 11,000 people nationally when related cases are included. Cyclosporiasis is an intestinal illness caused by a microscopic parasite typically spread through contaminated food or water, and it can cause prolonged watery diarrhoea and other gastrointestinal symptoms.