How long are you contagiuos with the stomache bug?

My 4 yr old got it and it lasted not a full day and my 15 month old stayed at my moms to aviod getting it , she came home a week later and 2 days after she was home she got it...I had cleaned everthing so she had to have contracted it from her sister which had been well for a week...they are now both at my moms because I have a 2 month old baby and we dont want him to get it...they have been over it now for a week but this week my mom has had it and now my dad has it now....oth girls have had the rotavirus vacc. this has been horrible and my parents are in their 7os so this has been hard for them...when would it be safe to get my girls back?