An outbreak of E. coli O157:H7 in children—associated with elk exposure

In September, 2009, a multi-jurisdictional outbreak investigation was initiated to determine the source of sporadic E. coli O157:H7 infection in three Colorado children from Jefferson and neighboring Park Counties, after state public health laboratories identified a common isolate pattern using pulse field gel electrophoresis (PFGE). Additional case finding efforts identified a total of 8 lab-confirmed primary cases in children aged 4-12 years, whose onset of illness ranged from July 25 to October 22. Included were two children who were hospitalized and later recovered from development of hemolytic uremic syndrome (HUS). Six of the eight children resided in Jefferson County; two lived in neighboring Park and Clear Creek Counties. Repeated case interviews showed only recreational exposure to multiple parks and sports fields in a mountainous Jefferson County community to be common among the children. Each of these fields were found to have intermittent heavy contamination with elk feces from four established herds in the community and 2/10 pooled fecal specimens from elk cultured positive for E. coli O157:H7. These isolates from the elk were found to be an identical PFGE match to the outbreak strain from the children. A case control study was conducted to identify specific behavioral risk factors for elk exposure and infection. Four age- and gender- matched controls were selected randomly for interview from a census of students attending each of the community schools where an ill child had also attended. The findings from this study will be presented.