Randomized controlled trial assessing infectious disease risks from bathing in fresh recreational waters in relation to the concentration of Escherichia coli, intestinal En terococci, Clostridium perfringens, and Somatic ColiphagesRandomized controlled trial assessing infectious disease risks from bathing in fresh recreational waters in relation to the concentration of Es cherichia coli, intestinal Enterococci, Clostridium perfringens, and Somatic Coliphages