Chickenpox is a common childhood illness rash, which is characterized by its very contagious. It reflects the primary infection by the varicella-zoster virus, or VZV, virus of the family Herpesviridae. In over 90% of cases it occurs in children between 1 and 15 years. Its incubation period is 14 days on average (10 to 21 days).

Bénigne In healthy children, it can be frightening and deadly in adults not immunized, the immunocompromised, pregnant women and newborns.

The virus of the varicella zoster, as its name suggests, is the cause of chicken pox and shingles. It is part of the Herpesviridae. The first infestation leads the table of chicken pox virus then takes refuge in the sensory nerve ganglia where it can remain latent for decades. Its secondary is responsible reactivation of shingles.

The virus is present in the nose and throat before the eruption and the blisters during the latter. The contagiousness starts between one and two days before the eruption. It ends at the complete recovery (loss of all crusts from the healing of blisters). This may be extended in severe disease.

The pénètrerait virus in the body through the respiratory tract, reaching the lymph nodes for them multiply, then spread after the incubation period, in the throat and skin.

In temperate countries, over 90% of adults have had chickenpox during childhood or adolescence (usually between 1 and 9 years). The disease is often said later in tropical countries.

The incidence is highest in winter and spring. The monitoring of changes in the incidence in France is carried out by the network Sentinels of Inserm.

The most late are significantly more serious.

* General Malaise and low-grade fever a few hours before the rash.
* Rash:
O Small pink macules appear initially. They will soon be covered with blisters dew drops, which within three days will dry out and form a crust. It may remain transient hypopigmentées lesions, or scars.
O Generally these lesions appear first on the scalp and then on the chest and mucous membranes, then on the members, with respect for palmar-plantar regions, and finally in the face.
O The different series of injuries staggered over time so that coexist different types of injuries all over his body.
O The importance of the rash varies greatly from one individual to another.
* Difficulty in eating because of the blisters that form sometimes in the mouth.
* Big itching (pruritus).
* Cough important in some cases.

It is most often evident before the appearance of the rash and the notion of a contact in the two weeks leading up with another patient.

In exceptional cases, the diagnosis can be confirmed by the research of the virus in vesicles.

The search for antibodies against chickenpox (serology) may be made but there are some cross-reactions with antibodies against other herpesviruses. This research may be helpful to target people to be vaccinated (no antibodies).

Natural evolution
* Healing in 7 to 16 days for adults and children.
* Generally immunity is definite but it is possible, though rare, to observe a second chickenpox in a matter immunocompromised.
* The virus remains dormant and can later be found to cause shingles.

Varicella complicated
Although benign in the vast majority of cases, chickenpox can be complicated, especially in immunocompromised patients, infants, adults, pregnant women.

* Impetigo: bacterial superinfection in the event of scratching skin lesions
* Pneumonia varicelleuse: it is not uncommon in adults, and is manifested by acute pulmonary symptoms aspécifiques (cough, high fever, difficulty breathing, hemoptysis).
* Acute cerebellar ataxia: is the child of benign developments (one in 4000).
* Reye Syndrome: encephalitis is a serious, outstanding, due to take anti-inflammatory drugs, such as aspirin.

Among mundane forms of childhood illness is not serious and is only a matter of treating the symptoms: fever, itching.

At the eruptive phase:

* Avoid the child scratching (cut nails flush, or even use of mittens at the small child), because this can cause unsightly scars skin final. It may also give the child a bath of warm water in which there is dissolving a little baking soda to soothe the itch. An antihistamine may be prescribed by your doctor.
* Isolate the child of his peers and adults who have not been infected during their childhood. The eviction school and is likely to be decided on a case-by-case basis. The contagion starting most of the time before symptoms have been identified, it is usually too late to completely halt the transmission of the disease.
* Consult a doctor prescribe it antiseptics and antibiotics sometimes only in the case of superinfection (impétiginisation).
* Give plenty to drink.
* Do not give anti-inflammatory containing acetylsalicylic acid, aspirin type, or steroidal anti-inflammatory (corticosteroids, as well as local application that oral - what happens in children suffering from severe eczema --), or non-steroidal (including type ibuprofen), which are formally contra-indicated because of the risk - rare - Reye's
* Do not use creams, gels, talc, ointments, which increase the risk of infection by maceration.

In severe forms, antiviral treatment is prescribed: aciclovir is consistently effective, with exceptional resistance.

It is performed in a single injection in children under the age of 12, and two injections spaced one to two months, with the older child. It can be done in isolation, or grouped (vaccination against varicella, rubella, mumps and measles).

The efficiency of nearly 90%, and in case of chickenpox, it is significantly less severe. In addition, it should theoretically reduce the risk of shingles, but it has not been formally proven. The effectiveness of vaccination appears, however, significantly decrease over time.

Immunization remains safe with less than 3 accidents per 100000 doses, the latter occurring mainly in children immunocompromised.

In Switzerland
The indications for the varicella vaccine are as follows:

* Young people aged 11 to 15 with no history of chickenpox.
* News from the age of 12 months not immune (IgG negative) presenting risks of complications following:
O Leukemia; cancer; before immunosuppressive therapy or transplantation; the HIV-infected child, before immunodeficiency.
O Children suffering from severe eczema.
O People in close contact with patients above (parents, siblings).
O Medical staff.
O Catch up vaccine among adults under 40 with no history of chickenpox.

In case of uncertain history, a serology can be obtained, but it could also proceed directly to the vaccination. In the directions above, the cost of vaccination is supported by funds under the compulsory health insurance scheme.

Other countries
In other countries, vaccination is much more systematic (United States, Canada, Taiwan ...), leading to a sharp decrease in disease and severe forms thereof as well as a significant decrease in terms of cost (drugs, absenteeism, childcare ...).

Other preventive treatments
In some cases, the injection of specific immunoglobulin can prevent the onset of the disease or reduce its severity. They are used primarily in cases of contraindication to vaccination (immunosuppression).

The aciclovir has also shown some effectiveness when it is given soon after the contage (contamination).

Varicella and pregnancy
Among pregnant women this disease is serious for the woman and fetus:

* In pregnant women, chickenpox is responsible for pneumonia fatal in 10% of cases
* At the fetus, chickenpox can cause birth defects if the disease is contracted five months before
* In neonates, a neonatal congenital varicella may occur if the mother has had chickenpox few days before or after birth. Neonatal congenital varicella This is a very serious with a mortality of 20%.

Read also Varicella