Just why would you?
I work in a clinic, think dentist, opticians, out patient unit, this week a lady came in with both her dc's for a last minute appointment.
I casually said " oh your kids have broken up already ?" To which she replied " oh no we all came down with d&v bug and I didn't want to waste the chance to get this done before the holidays."
I was about to say " but you're all feeling better now ?" When she literally shot into our staff toilets and the little one turned green and was sick 
Now I'm lying here with, you guessed it D&V worried about my other patients and colleagues.
I did sterilise everything after they left I kicked them out
Why do people do this ?