Definition of chickenpox

La varicella is a highly contagious disease caused by chickenpox virus-zone (VZV), transmitted by direct contact with the blisters of an infected person or through the respiratory tract.

It causes epidemics which, in temperate countries, usually occur in late winter and early spring.

La contagious period starts 24 to 48 hours before the first pimples and redness appear and lasts about a week, until the blisters are dry and crusty. Sometimes the child has to be kept at home because of the contagion, depending on the policy of the school or daycare he attends.

Usually, people who had chickenpox as children have made antibodies that protect them against this disease for the rest of their lives. However, the varicella zoster virus is not completely eliminated from the body. Indeed, it takes refuge in the nerves, where it goes into dormancy. There it is beyond the reach of the immune system. But under certain conditions, it can reactivate, migrate up the nerves to the skin, and then cause shingles.

Possible complications

In most cases, chickenpox is a mild illness. The most common complication is infection of skin lesions with bacteria, called bacterial superinfection, which can occur when the child is scratching, for example. It is usually not serious, except in rare cases where the infection is caused by bacteria such as streptococcus.

Babies, pregnant women, and people with weakened immune systems can have more serious complications if they get chickenpox, such as pneumonia or, in rare cases, encephalitis. In addition, in pregnant women, if chickenpox occurs for example during the first 4 months of pregnancy, it can cause malformations in the fetus (in 1% to 2% of cases).