Possibly lost amongst many other pressing infectious disease issues such as yellow fever, Zika, and antibiotic resistance was a report released by CDC assessing public swimming pools. The bombshell contained in the report is the finding that 80% of pools have been closed for safety violations. While I believe that many of these safety violations might be the result of bureaucratic intricacies and pose no danger, those that deal with diminished chlorine, for example, are likely serious as they potentially can allow dangerous microbes to pass from one swimmer to another. Rotavirus, E.coli O157, and cryptosporidium are pathogens that can find a poorly disinfected pool hospitable.
While it is unequivocally important to highlight the appropriate disinfection procedures that must be followed for optimal safety, it is not a good state of affairs when people have to be warned not to swim in a public pool if they have diarrhea. A floating turd, which I have seen on multiple occasions (in fact it's how, as a child taking swimming lessons at the YMCA, I first learned what the word feces meant), is an identifiable hazard that can be easily seen, avoided, and remedied. Diarrhea, to unaware swimmers, to use threat analysis terms is an unknown unknown.
Why people with diarrhea think it's OK to merge their "stream" with that of the pool's I will never know.