You are right, though it was "treated" running water, SirJohnSirJohn5. And effective waste water treatment, including chemical additives.

You are right that better hygiene is critical. I am frequently in a hospital these days, and I notice one poster by public health, infection control people that says hand washing is perhaps the most important step in disease control.

But it is the loss of steps that make us vulnerable, ... steps like antibiotics and, especially, relatively low cost and effective immunization.