Chickenpox (varicella) is a common
infectious viral infection with the varicella-zoster virus (VZV), one of
the herpes viruses. The characteristic feature of chickenpox is a rash
that starts out as red spots that turn into pimple like itchy blisters,
which is often accompanied by fever. After the blister bursts, a dry
crust forms. While chickenpox is usually benign and self-limiting in
otherwise healthy children, the disease is often more severe in
immunosuppressed individuals, neonates, adolescents and adults.
Signs and Symptoms of Chickenpox
The first symptoms appear after the
incubation period, about 14 days after exposure to the virus. They are
usually non-specific complaints such as headache, depression, fever and
loss of appetite. One or two days after the first symptoms, a rash
appears which may itch, start with a few red spots on the trunk, which
will rapidly spread out to cover the front and back of body. The limbs,
face, scalp, mouth and tongue can be affected. The average number of
vesicles is 200 but as many as 500 or even more may develop in certain
cases. The spots are initially flat but soon appear to be small blisters
as fluid collects in them. After a few weeks the blisters rupture to
form crusts which drop off slightly pink depressed areas of skin.
As the skin heals, the rash usually
disappears. However, scars can develop if they were scratched and became
infected. Spots on the face can lead to facial scars. Once a person has
had chickenpox, he will normally get immunity against chickenpox and
won't have it again. However, the chickenpox virus stays inactive
(dormant) in a person's body for his lifetime. Later in life (usually in
older adult years), the virus may become active again and cause shingles
(herpes zoster).
In young children these symptoms are often
mild and short-lived. In older children, adolescents and adults, they
tend to be more severe. They usually have more chickenpox blisters and
the other symptoms associated with the illness are usually more
persistent.
Adults with chickenpox may need to be
admitted to the hospital for care. People with impaired immune systems
may have more severe and longer lasting symptoms of illness when they
have chickenpox.
Reliable data on the local epidemiology of
chickenpox are limited. Almost everyone, however, will be exposed to
varicella-zoster virus over their lifetime, making the annual incidence
of chickenpox in any country about the same as the cohort of children
born in a given year. The age-related incidence of chickenpox is known
to vary from one country to another, and climate plays an important
role.
