If you go to pick up a villager and they are sick - they will cough.
But other than 'Detail' each one or try to move them I don't think there is any way to tell.
I have noticed that they will sometimes just sit not far from the well - but not always - sorry
The easiest way is to click detail then click on the center arrow key and just scroll through them all. Just watch the top "bar" that usually says healthy or elderly - it will say sick.
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Huggies - Pam
I live in my own little world - I like it there - Everyone knows me.