E. coli tests of romaine fields where investigators traced contaminated lettuce did not turn up outbreak strains, so the FDA will move to an in-depth “root-cause” investigation for three outbreaks.

As the FDA awaits final results from extensive E. coli tests of romaine lettuce farms in one California growing region, it says outbreak illnesses are slowing, though two separate outbreaks have popped up.

Health officials warned people not to eat romaine lettuce from Salinas, Calif., because it is likely the source of an E. coli outbreak.

Investigators announced an E. coli outbreak and a trace of romaine lettuce, prompting a recall of salad kits and bowls sold at many stores in 22 states.

Public health authorities are investigating 47 illnesses from scombrotoxin fish poisoning linked to yellowfin tuna that may have been sold fresh or frozen.