MODEL RELEASED. Girl with chickenpox. Four-year- old girl with chickenpox or varicella, bathing with her uninfected younger sister. Chickenpox is a common infectious disease of childhood caused by the varicella-zoster virus. Symptoms are headache and fever, followed by a rash of small, red, itchy spots that become fluid-filled blisters within a few hours. It is rare to have chickenpox twice, as the first infection normally gives immunity for life. While the disease is not usually serious in children, it tends to be more serious in adults or babies. It can be fatal to people of any age. Treatment is to use soothing lotion and anti-fever medication. Vaccination can prevent chickenpox.