MMWR reports that ten outbreaks of gastrointestinal illness among school children at nine different schools were reported during February 2003–May 2004 to the Massachusetts Department of Public Health (MDPH). These outbreaks occurred among children who ate lunch provided by the schools and were characterized by short incubation periods and short durations of illness.
The clinical and epidemiologic characteristics of the outbreaks were similar to those of previously reported outbreaks of vomiting associated with burritos served at multiple schools in the United States in 1997–1998 (1,2). Epidemiologic investigation of the 1997–1998 outbreaks implicated burritos made with flour tortillas as the suspect vehicle; no etiologic agent was identified, but symptoms suggested either a biotoxin or chemical agent.
This report describes epidemiologic and laboratory findings from three of the 10 outbreaks in Massachusetts. Consumption of flour tortillas from a single manufacturer was significantly associated with illness. Preliminary results indicated elevated levels, relative to common industry practices, of potassium bromate and calcium propionate in the implicated tortillas. School officials should be aware of the need for rapid action during outbreaks with short incubation periods and short durations and should notify local and state health officials immediately to ensure rapid response and collection of epidemiologic information, clinical specimens, and food samples.