NEW: The acting FDA commissioner says shredded lettuce is still the leading suspect behind the foodborne parasite outbreak sickening people across the U.S., wit

NEW: The acting FDA commissioner says shredded lettuce is still the leading suspect behind the foodborne parasite outbreak sickening people across the U.S., with investigators tracing the source back to Taylor Farms. But not every Taylor Farms product is affected. As @​jonathanserrie explains, the …