Hi. This is true that FEVER-VIRUS is a self-limiting disease. But the patient needs at least a treatment for symptomatic relief of fever, bodyache and may be running nose ( if she has). This is a fever caused due to infection by the virus which has no definite treatment ( fever and symptoms are treatable , virus is not) . This is definitely contagious and can affect the others with reduced immunity. People with strong immunity may not get affected or get a very mild attack. You can give her paracetamol according to the weight and may be anti-cold syrup if she has running nose. Ant other medications are given as per the symptoms which are very varied every-time . Keep her properly hydrated. Ask her to take full bed rest as this helps for early recovery. Visit a Doctor if other problems like stomach ache, vomiting , loose motions or anything unusual develops.