Chickenpox is a highly contagious disease caused by primary infection with varicella zoster virus (VZV).

It usually
starts with a vesicular skinrash mainly on the body and head rather than on the limbs. The rash develops into itchy,
raw pockmarks, which mostly heal without scarring. On examination, the observer typically finds skin lesions at
various stages of healing and also ulcers in the oral cavity and tonsil areas. The disease is most commonly
observed in children.
Chickenpox is an airborne disease which spreads easily through coughing or sneezing by ill individuals or through
direct contact with secretions from the rash. A person with chickenpox is infectious one to two days before the rash
appears.] They remain contagious until all lesions have crusted over (this takes approximately six
days). Immunocompromised patients are contagious during the entire period as new lesions keep appearing.
Crusted lesions are not contagious.
Chickenpox has been observed in other primates, including chimpanzees[5] and gorillas.
The origin of the term chicken pox, which is recorded as being used since 1684,] is not reliably known. It has been
said to be a derived fromchickpeas, based on resemblance of the vesicles to chickpeas, or to come from the rash
resembling chicken pecks. Other suggestions include the designation chicken for a child (i.e., literally 'child pox'), a
corruption of itching-pox, or the idea that the disease may have originated in chickens.] Samuel Johnson explained
the designation as "from its being of no very great danger."

Signs and symptoms

A single blister, typical during the early stages of the rash

Male with varicella disease

The back of a 30-year-old male after five days of the rash

The early (prodromal) symptoms in adolescents and adults are nausea, loss of appetite, aching muscles, and
headache. This is followed by the characteristic rash or oral sores, malaise, and a low-grade fever that signal the
presence of the disease. Oral manifestations of the disease (enanthem) not uncommonly may precede the external
rash (exanthem). In children the illness is not usually preceded by prodromal symptoms, and the first sign is the rash
or the spots in the oral cavity. The rash begins as small red dots on the face, scalp, torso, upper arms and legs;
progressing over 1012 hours to small bumps, blisters and pustules; followed by umbilication and the formation of
scabs.
At the blister stage, intense itching is usually present. Blisters may also occur on the palms, soles, and genital area.
Commonly, visible evidence of the disease develops in the oral cavity & tonsil areas in the form of small ulcers which
can be painful or itchy or both; this enanthem (internal rash) can precede the exanthem (external rash) by 1 to 3
days or can be concurrent. These symptoms of chickenpox appear 10 to 21 days after exposure to a contagious
person. Adults may have a more widespread rash and longer fever, and they are more likely to experience
complications, such as varicella pneumonia.

Because watery nasal discharge containing live virus usually precedes both exanthem (external rash) and enanthem
(oral ulcers) by 1 to 2 days, the infected person actually becomes contagious one to two days prior to recognition of
the disease. Contagiousness persists until all vesicular lesions have become dry crusts (scabs), which usually
entails four or five days, by which time nasal shedding of live virus also ceases.
Chickenpox is rarely fatal, although it is generally more severe in adult men than in women or children. Non-immune
pregnant women and those with a suppressed immune system are at highest risk of serious complications. Arterial
ischemic stroke (AIS) associated with chickenpox in the previous year accounts for nearly one third of childhood
AIS. The most common late complication of chickenpox is shingles (herpes zoster), caused by reactivation of
the varicella zoster virus decades after the initial, often childhood, chickenpox infection.

Diagnosis
The diagnosis of varicella is primarily clinical, with typical early "prodromal" symptoms, and then the
characteristic rash and oral-cavity sores. Confirmation of the diagnosis can be sought through either examination of
the fluid within the vesicles of the rash, or by testing blood for evidence of an acute immunologic response.
Vesicular fluid can be examined with a Tzanck smear, or better by testing for direct fluorescent antibody. The fluid
can also be "cultured", whereby attempts are made to grow the virus from a fluid sample. Blood tests can be used to
identify a response to acute infection (IgM) or previous infection and subsequent immunity (IgG).
Prenatal diagnosis of fetal varicella infection can be performed using ultrasound, though a delay of 5 weeks following
primary maternal infection is advised. A PCR (DNA) test of the mother's amniotic fluid can also be performed,
though the risk of spontaneous abortion due to the amniocentesisprocedure is higher than the risk of the baby
developing fetal varicella syndrome.

Prevention[edit]

Hygiene measures[edit]
The spread of chickenpox can be prevented by isolating affected individuals. Contagion is by exposure to respiratory
droplets, or direct contact with lesions, within a period lasting from three days prior to the onset of the rash, to four
days after the onset of the rash. The chickenpox virus is susceptible to disinfectants, notably chlorine
bleach (i.e., sodium hypochlorite). Also, like all enveloped viruses, it is sensitive to desiccation, heat and detergents.

Vaccine[edit]
Main article: Varicella vaccine
A varicella vaccine was first developed by Michiaki Takahashi in 1974 derived from the Oka strain. It has been
available in the US since 1995 to inoculate against the disease. Some countries require the varicella vaccination or
an exemption before entering elementary school. Protection from one dose is not lifelong and a second dose is
necessary five years after the initial immunization, which is currently part of the routine immunization schedule in the
US. The chickenpox vaccine is not part of the routine childhood vaccination schedule in the UK. In the UK, the
vaccine is currently only offered to people who are particularly vulnerable to chickenpox. A vaccinated person is
likely to have a milder case of chickenpox if infected.

Treatment
Treatment mainly consists of easing the symptoms as there is no actual cure of the condition. Some treatments are
however available for relieving the symptoms while the immune systemsuppresses the virus in the body. As a
protective measure, patients are usually required to stay at home while they are infectious to avoid spreading the
disease to others. Also, sufferers are frequently asked to cut their nails short or to wear gloves to prevent scratching
and to minimize the risk of secondary infections.
The condition resolves by itself within a couple of weeks but meanwhile patients must pay attention to their
personal hygiene. The rash caused by varicella zoster virus may however last for up to one month, although the
infectious stage does not take longer than a week or two.
Although there have been no formal clinical studies evaluating the effectiveness of topical application of calamine
lotion, a topical barrier preparation containing zinc oxide and one of the most commonly used interventions, it has an
excellent safety profile.[38] It is important to maintain good hygiene and daily cleaning of skin with warm water to avoid
secondary bacterial infection.]Scratching may also increase the risk of secondary infection.
Acetaminophen (paracetamol) but not aspirin may be used to reduce fever. Aspirin use by someone with chickenpox
may cause the serious, sometimes fatal disease of the liver and brain,Reye syndrome. People at risk of developing
severe complications who have had significant exposure to the virus may be given intra-muscular varicella zoster
immune globulin (VZIG), a preparation containing high titres of antibodies to varicella zoster virus, to ward off the
disease.
Antivirals are sometimes used.

Children[edit]
If oral acyclovir is started within 24 hours of rash onset it decreases symptoms by one day but has no effect on
complication rates. Use of acyclovir therefore is not currently recommended for immunocompetent individuals (i.e.,
otherwise healthy persons without known immunodeficiency or on immunosuppressive medication). Children
younger than 12 years old and older than one month are not meant to receive antiviral medication unless they are
suffering from another medical condition which would put them at risk of developing complications. [
Treatment of chickenpox in children is aimed at symptoms while the immune system deals with the virus. With
children younger than 12 years cutting nails and keeping them clean is an important part of treatment as they are
more likely to scratch their blisters more deeply than adults.
Aspirin is highly contraindicated in children younger than 16 years as it has been related with a potentially fatal
condition known as Reye's syndrome.[

Some parents believe that it is better for children to contract chickenpox than to get the vaccine, and they
deliberately expose their children to the virus, sometimes by taking them to "chickenpox parties." Some doctors
counter that children are safer getting the vaccine, which is a weakened form of the virus, than getting the disease,
which can be fatal.

Adults[edit]
Infection in otherwise healthy adults tends to be more severe. Treatment with
antiviral drugs (e.g. acyclovir or valacyclovir) is generally advised, as long as it is started within 2448 hours from
rash onset. Remedies to ease the symptoms of chickenpox in adults are basically the same as those used on
children. Adults are more often prescribed antiviral medication as it is effective in reducing the severity of the
condition and the likelihood of developing complications. Antiviral medicines do not kill the virus, but stop it from
multiplying. Adults are also advised to increase water intake to reduce dehydration and to relieve headaches.
Painkillers such as paracetamol (acetaminophen) are also recommended as they are effective in relieving itching
and other symptoms such as fever or pains. Antihistamines relieve itches and may be used in cases where the
itches prevents sleep, because they are also sedative. As with children, antiviral medication is considered more
useful for those adults who are more prone to develop complications. These include pregnant women or people who
have a weakened immune system.
Sorivudine, a nucleoside analogue has been reported to be effective in the treatment of primary varicella in healthy
adults (case reports only), but large-scale clinical trials are still needed to demonstrate its efficacy.
After recovering from chickenpox, it is recommended by doctors that adults take one injection of VZV immune
globulin and one injection of varicella vaccine or herpes zoster vaccine.