Chicken pox is an acute infectious disease accompanied by fever and a characteristic vesicular rash on the skin. Children up to ten years of age are the main victims, but after infection, immunity is guaranteed for life. The causative agent is a filterable virus Varicella zoster, which is transmitted from an infected person to a healthy one mainly by means of air droplets (fine sprays of saliva during coughing or sneezing). Symptoms include a rise in temperature and a skin rash which becomes blisters which erupt, and resultant considerable and uncomfortable irritation.
While generations of children have been infected with chickenpox and survived with little more than a scar, a small percentage will develop serious complications such as pneumonia, bacterial infections and arthritis.
According to the US Centers for Disease Control and Prevention (CDC), more than 90% of infections, two-thirds of varicella-related hospitalizations and nearly half of varicella-related deaths occur in children. The incidence of disease had been highest among children ages 5 to 9 in the past but now occurs most frequently in children ages 1 to 4.