Anonymous wrote:The incubation period was over and other kid was not contagious.

"With norovirus — the most common cause of viral gastroenteritis in adults — you're contagious from the moment you begin to feel ill. Symptoms appear within one to three days of exposure. Although you typically feel better after a day or two, you're contagious for at least three days after you've recovered. Some people may be contagious for up to two weeks after recovery. Also, children are often contagious for a longer period than are adults."
http://www.mayoclinic.org/diseases-conditions/viral-gastroenteritis/expert-answers/stomach-flu/faq-20057899

Google is your friend, use it to avoid spreading misinformation.

OP, you should definitely tell mom so she can look out for symptoms. You didn't do anything wrong and handled the situation well, there is no rational reason she would be upset at you, and more likely will appreciate that you let her know.

I do not know much about this so I cannot judge this mother for taking her child to the playground.

I would mention it to your charge's parents when they get home. It would only be the right thing to do OP.

That way they can be on full alert if their child shows any symptoms.

You did nothing wrong and I am sure she knows that.

The incubation period was over and other kid was not contagious.

TELL the mom !

Tell the mom. You handled it well. That was really selfish.

YES. Absolutely tell the parents so they know what to look for!

Yes, I would advise MB to put a call into the ped, just in case there's any further recommendations.
You did nothing wrong at the park.

I took DC to the park earlier today and he was happily running around, picking up woodchips, and even chasing around/being chased by a little girl who was there with her mom. After about an hour of chatting with the mom and watching them run around I asked how old her little girl is. The mom said "Oh, she's 2, but she's lost a lot of weight so she doesn't look it right now. She had the norovirus, actually she still has some diarrhea." I was really freaked out that DC was playing around her. They never actually touched, but stood close to each other and were touching and using the same playground equpment. I left with him immediately after she said that (politely) and cleaned his hands with a sanitzing wipe in the car. He also had a bath right when we got home, but I'm still worried. I just Google'd it and yep, it is super contagious and dangerous for young children. Why in the world would you bring a child who is still showing symptoms a serious virus to the playground!? In any case, should I tell the baby's parents about this? He is 13 months old.