A swimming pool E. coli O157:H7 outbreak in Pennsylvania in June 2021 sickened 15 children, according to the CDC‘s Morbidity and Mortality Weekly Report. The patients were ages 4 to 14; all swam at the pool on May 31, 2021, the opening date, and had no other known common exposure.
On June 7, 2021, the Pennsylvania Department of Health received multiple reports of gastrointestinal illness from patrons of a community swimming pool. Two people reported positive Shiga toxin-producing Escherichia coli (STEC) and Clostridioides difficile tests from stool specimens. The government ordered the pool closed, and initiated an outbreak response.
Confirmed cases were defined as isolation of E. coli O157:H7 or detection of Shiga toxin or Shiga toxin genes from stool specimens of persons who visited the pool during May 31 to June 7, 2021. Probable cases are defined as three or more loose stools in a 24 hour period, accompanied by nausea, vomiting, fever, or cramps, in persons who visited the pool during that time frame.
There were 15 total cases, with nine confirmed and six probable. The total number of pool visits on the opening date is unknown. Symptom onset occurred during June 2 to June 4, 2021. Thirteen patients sought medical treatment. Six of the patients were hospitalized. Four received antibiotics for C. difficile. Antibiotics are not recommended for E. coli infections since they can increase the risk of developing hemolytic uremic syndrome (HUS). No cases of HUS were reported.
Pool inspection revealed an automatic chlorinator malfunction. Record keeping was inconsistent with local requirements. The few records that were available demonstrated at least one instance of no detectable chlorine. The two pathogens are susceptible to chlorine.
Enteric disease outbreaks caused by multiple pathogens are rare, and co-infections with C. difficile and other pathogens are unusual but possible, as indicated by this outbreak. This swimming pool E. coli O157:H7 outbreak shows that recreational waters should always be properly treated and maintained, and anyone experiencing diarrhea should not go into communal swimming pools.
