chickenpox

A false-colour electron micrograph of the chickenpox virus Varicella zoster. Viruses are minute infectious particles that can only multiply if they invade a living cell and use its genetic machinery. It is therefore difficult to find a treatment that attacks the virus itself but leaves the host cell unharmed. A healthy body produces antiviral proteins to prevent the infection from spreading to adjacent cells. Though highly contagious, chickenpox usually creates a lifelong immunity. The chickenpox virus is part of the herpes family of viruses.

Common, usually mild disease, caused by a virus of the herpes group and transmitted by airborne droplets. Chickenpox chiefly attacks children under the age of ten. The incubation period is two to three weeks. One attack normally gives immunity for life.

The temperature rises and spots (later inflamed blisters) develop on the torso, then on the face and limbs. The sufferer recovers within a week, but remains infectious until the last scab disappears.

The US Food and Drug Administration approved a chickenpox vaccine in March 1995. Based on a weakened form of the live virus, the vaccine is 70-90% effective. A vaccine is available in Europe, but is only used in children with an impaired immune system.