Shigellosis in day care centers: use of plasmid analysis to assess control measures.

Spread of shigellosis within day care centers is difficult to control, and illness may spread into the community. We investigated two sequential outbreaks of diarrhea caused by multiply resistant Shigella sonnei in children at day care centers in 2 neighboring counties in Florida. We used plasmid analysis to identify a single epidemic strain causing both outbreaks and to assess the control measures used. One of the control measures, keeping ill children from attending the center, did not prevent spread of illness in the community.