US health officials are probing Taco Bell's role into an outbreak of explosive diarrhoea 'cyclosporiasis', which has spread to 34 US states. Earlier, Taco Bell said it was "unable to sell lettuce, cilantro, onion, pico de gallo and guacamole due to a nationwide recall". Michigan, the hardest-hit state with 3,309 cases, said lettuce or salad greens are likely behind outbreak.