A school waterborne outbreak involving both Shigella sonnei and Entamoeba histolytica.

In an outbreak of gastroenteritis affecting 730 students, Shigella sonnei and Entamoeba histolytica were isolated from the stool specimens of patients. Environmental investigations revealed the source of infection to be contamination of underground well water by sewage from a toilet. The outbreak ended with the closure of the well water supply. To avoid such problems, institutions and other groups that maintain their own wells, including schools and summer camps, need to be vigilant about maintenance and check for potential contamination.