Outbreak of Shiga-Toxin Escherichia coli O157 Illustrates the Risk of Small Plastic Pools

BACKGROUND:   On May 13, 2014, a Kansas county health department notified the Kansas Department of Health and Environment of two children with illness caused by Shiga toxin-producing Escherichia coli (STEC) who attended a house party; additional ill individuals were reported among party attendees.  Activities included playing with chicks, bottle feeding a calf, and playing in a small plastic pool that was purchased and filled the day of the event.  Attendees had a picnic lunch; each person ate food brought by his or her own family. 

METHODS:   Families of ill children were interviewed in person with a special standardized questionnaire.  A confirmed case was defined as isolation of STEC O157 from a clinical specimen with pulsed-field gel electrophoresis (PFGE) Xba1 pattern EXHX01.1379 and Bln1 pattern EXHA26.0630.  Persons with primary cases attended the house party on May 5, 2014; persons with secondary cases became symptomatic with diarrhea one to ten days after having contact with a person with a primary case.  Fecal samples collected from the calf were tested by the United States Department of Agriculture’s Agricultural Research Service in Lincoln, Nebraska.

RESULTS:   Multiple families with children attended the party; no other common exposures were identified.  Four children had confirmed primary cases; one child had a confirmed secondary case.  Persons with confirmed cases ranged in age from 2 to 3 years.  Three (60%) children were hospitalized, and two (40%) developed hemolytic uremic syndrome.  All stool specimens tested positive for STEC O157 with indistinguishable PFGE patterns.  No STEC O157 was isolated from calf fecal samples and no illnesses were reported by any attendee prior to the event.

CONCLUSIONS:   Four confirmed cases of STEC O157 were associated with attendance at a house party.  Parents reported that not all ill children had direct contact with the calf.  However, attendees did report calf manure in the yard where children were playing.  The four primary cases all played in the pool where water was reportedly splashed in their faces.  The confirmed secondary case played in another plastic pool with an ill child who had a primary case and had a fecal accident in the pool.  Investigators hypothesize that accidental ingestion of contaminated water while playing in the plastic pools is likely to have been the source for both primary and secondary cases.  Plastic pools filled with tap water should not be used for gatherings especially if livestock is present.  Ill children should not be allowed in plastic pools while still infectious.