An outbreak of E. coli O157:H7 last August, traced to a lake at Cowan’s Gap State Park in Pennsylvania, sickened at least 18 people and may have sickened as many as 42, the Pennsylvania Department of Health reports in the winter edition of its EpiNotes epidemiology newsletter.

A majority of those affected were children.

After initial reports of E. coli infection among swimmers, the lake was closed to swimming, boating and fishing on Aug. 9, 2011.

According to the department’s final outbreak report, there were 13 confirmed and 5 probable illnesses. Ten of the 13 confirmed cases were hospitalized and 7 developed hemolytic uremic syndrome (HUS), a complication of E. coli infection that can lead to kidney failure. 

One case was known to be the result of secondary transmission — a person exposed to another infected person but not the lake water. Sixty-one percent of the case patients were 10 years old or younger.

An additional 24 people were classified as suspect cases because they had reported both gastrointestinal symptoms and exposure to the lake.

While the lake water did not test positive for E. coli O157:H7, health department officials wrote that the “epidemiology clearly indicates the lake as the source of transmission” because the lake was the only common factor among all of the cases, and all of the primary cases reported swimming in the lake.

Although investigators weren’t able to determine the original source of fecal contamination, they said it was likely a person who was swimming while ill.

According to the Environmental Protection Agency (EPA), bacterial contamination in recreational water is becoming an increasing problem. More and more beaches are closed each year for fecal contamination.

The Centers for Disease Control and Protection recommends the following precautions for those who use public water recreation facilities:


– Do not swallow swimming water

– Don’t swim when you have diarrhea in order to avoid spreading germs to others

– Shower and wash with soap before swimming in public areas, and wash hands after going to the bathroom before getting in the water


For parents of young children, the CDC recommends:


– Take kids on bathroom breaks or check diapers often.

– Change diapers in a changing area, not poolside

– Wash your children thoroughly (especially their rear end) with soap and water before swimming.


The EPA keeps a record of beaches that have been closed due to contamination, available on its website.