Chickenpox (Varicella):
A parent's guide for infants and babies

Chickenpox (varicella) is a rare infection, which is extremely serious in infants, caused by a virus of the herpes family. Infants who are infected are either infected because their mothers were infected during pregnancy (fetal or congenital varicella) or acquired the virus after they were born (postnatal varicella). Fetal varicella and congenital varicella are much more serious forms of this disease, and there is a high risk of malformations and death to the newborn. Postnatal varicella is less severe, and infants typically only have the classic chickenpox rash. This rash appears as tiny itchy, flat, red spots on the skin that raise into clear fluid-filled blisters that eventually crust over. A fever, headache, and occasional stomach pain may also be present with the rash. The rash usually first appears on the scalp, face, or chest and tends to be more prominent in the center of the body. 

People with chickenpox are contagious from 24–48 hours prior to the appearance of the rash and continue to be contagious up until a week after the onset of the rash. This disease is spread by respiratory secretions, such as from mucus or saliva, so it is especially important to keep unimmunized children and infants away from infected persons.