How long will the rotavirus usually last?

3-7 days. : Symptoms vary from day to day and from person to person. Illness usually begins 12 hours to 4 days after exposure & generally lasts for 3 - 7 days. Children may have only diarrhea or vomiting at first, but with progression become sufficiently ill to require hospitalization. Other symptoms may develop as the disease evolves; about 10% of children have only fever and vomiting upon admission.

Rotavirus: Rotavirus is a reoviridae that causes stomach flu, aka gastroenteritis. Symptoms may include watery diarrhea, nausea, vomiting, abdominal pain, fever, decreased appetite, dehydration as well as cough & runny nose. Symptoms often last 3 to 8 days.