Definition
Chickenpox is a highly contagious viral disease caused by a virus belonging to the family of herpes viruses, varicella-zoster. Preferentially affecting children, it is usually benign but can sometimes cause complications, especially when it occurs in adulthood. Contracted during pregnancy, the disease poses a risk to the embryo or fetus. Chickenpox is more serious for people whose immunity is deficient (eg, those with AIDS).
A person who contracted chickenpox is immune because the infection permanently protects against the disease. People who have had chickenpox in childhood are at risk of contracting it in adulthood. However, the disease may be more serious from adolescence.
The chickenpox virus can also cause shingles. Chickenpox is the first manifestation of infection with varicella-zoster virus, which is called primary infection. After recovery, the virus remains sleeping in the ganglia near the spinal cord. Under certain circumstances it may be reactivated and start to multiply. It then travels along the nerves emerging from one or more nodes, causing severe pain and a rash on the skin. This is known as shingles.
