I see them defacating the water all the time! The canadian Geese are a bit nasty!
I never experience 'duck itch' until last Tuesday. I was swimming off Union Cemetary in Laconia when a dozen ducks swam over to join us. That was funny to swim with ducks. Later when I got home I was itching all over with red rashes on my skin. After a good hot shower and aloe vera lotion, I was good to go.
And no I was not sun burned.