Hand Foot and Mouth question

This is my first nanny position so when I was hired, I regrettably didn’t iron out a lot of things - including how to handle sick NKs. I watch 10moB and he had a runny nose/cough for most of November. Now his snot is mostly gone but he’s been coughing a lot more. He has a small rash on both hands but nothing else major. DB mentioned the possibility of HFM in passing the other day but brushed it aside, saying he and MB were sure that wasn’t it.

I’m not planning on calling out anytime soon (a cough/runny nose isn’t enough for me to worry about my health tbh) and I’m almost sure it isn’t HFM (just a cough from excess mucus as a result of teething and the rashes could be anything in relation to that. Who knows though lol) but it made me think: if baby has HFM, should I call out? How long would I be out as a result? Should I have a discussion with NP about their expectation with sickness in the house? How do you guys typically handle that?