Chickenpox is a very infectious illness caused by one of a group of herpes viruses. Most children will get chickenpox when they are young and it is usually a mild illness. Once your baby has caught the virus, it can take between 10 days and 21 days for symptoms to appear. To know more about chickenpox in babies, Contact Dr. Promilla Bhutani’s Clinic, one of the best child Care specialist in south Delhi.