Chickenpox

Definition of chickenpox

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

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

The contagious period starts 24 to 48 hours before the first pimples appear and lasts about a week until the blisters are dry and crust. Because of the contagion, it is sometimes necessary to keep the child at home, according to the policy of the school or daycare he attends.

In general, people who have had chickenpox during their childhood 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, he takes refuge in the nerves, where he goes dormant. At this point, he is out of reach of the immune system. But under certain conditions, it can reactivate, migrate along the nerves to the skin, and then cause shingles.

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Possible complications of Chickenpox

In most cases, chickenpox is a mild disease. The most common complication is an infection of skin lesions by bacteria, called bacterial superinfection, which can occur when the child is scratching, for example. It is generally not serious, except in the rare cases where the infection is caused by a bacterium of the genus Streptococcus.

Babies, pregnant women and people with weakened immune systems may have more serious complications if they develop 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).

Symptoms of Chickenpox

In someone who has been in contact with the virus, symptoms usually appear within 14 to 16 days of infection.

For a period of 5 or 6 days at most:

a slight fever ;
of red breakouts, that resemble insect bites, sometimes spread all over the body (even mucous membranes);
the buds turn into small round blisters, filled with a clear liquid;
The itching.

After a few days, as they appear, the blisters dry and form a crust. At this point, they are no longer contagious.

People at risk for Chickenpox

Varicella can be contracted at any age, but 90% of cases occur before the age of 10.

Prevention of chickenpox

Basic preventive measures

For a long time, chicken pox was unavoidable and it was preferred that children contract it at a very young age, while it is more benign. Since 1998, Canadians and French can receive varicella vaccine (Varivax III in Canada, Varivax in France, Varilrix in France and Canada).

Vaccination against chickenpox has been included in the Quebec Childhood Immunization Program since 2006, but not in France. It is usually given at 12 months of age. Adolescents and adults who have never had chickenpox can also receive it (contraindications apply). The need and effectiveness of a booster dose have not been established.

According to US scientific studies, vaccination provides protection for a minimum of 15 years. In Japan, where the first varicella vaccine (of another brand name) was manufactured, studies show that immunity is still present 25 years after vaccination. The effectiveness rate of varicella vaccine ranges from 70% to 90%. On the other hand, in people who have not been completely immunized, the vaccine can nevertheless reduce the severity of the symptoms. A large study in the United States indicates that vaccination resulted in a significant reduction in varicella cases (up 90%) and a decrease in the number of hospitalizations and deaths caused by this disease.

There is also Canada a combination vaccine called MMR-Var (Priorix-Tetra) which offers protection against four infectious diseases in one injection: chicken pox, measles, mumps, and rubella.

Measures to prevent aggravation and complications

Encourage children not to scratch their pimples.
Cut nails and wash children’s hands regularly to prevent further skin infection if they scratch.
People who are more likely to have complications, such as pregnant women who have never had chickenpox and people with weakened immune systems, have an advantage in avoiding physical contact with affected children and with people. Shingles (in times of crisis only), because these people can also transmit the chickenpox virus.

Risk factors

Be in contact with a contagious person.

The treatment of chickenpox

Treatment of chickenpox in children under 12 years

In children under 12 years, the disease is usually mild and takes its course in about ten days. Keep them at home if they do not feel well, allow them to sleep a lot, and make sure they do not become infected by scraping the blisters. If the infection develops, it may require antibiotics.
To reduce fever: paracetamol but no aspirin (ASA or acetylsalicylic acid), which can cause Reye’s syndrome in children with chickenpox.
To relieve itching: baths of warm water followed by an application of calamine; in some cases, the doctor may also prescribe antihistamines. The application of cold water compresses on the lesions also helps to relieve the itching.
Note. If the child seems to be suffering or the fever is high, see a doctor.
For newborns and children with weakened immune systems, the doctor usually prescribes an antiviral drug.

In adults and children over 12 years

In adults and children over 12, symptoms may be more pronounced, including fever. To reduce and accelerate the cure, it may be necessary to prescribe an antiviral: aciclovir (Zovirax in France and Canada, Apo-Acyclovir in Canada, etc.), famciclovir (Famvir) or valacyclovir ( Valtrex) in Canada. The faster this medication is taken, the more effective it is. It should be taken within 24 hours of the appearance of the vesicles. In France, only intravenous Zovirax has an indication in complicated chickenpox or in the immunocompromised subject, the newborn, the pregnant woman …

People at risk

For some people, chickenpox is more likely to cause complications. The “at risk” who have been exposed to the chickenpox virus (contact with a contagious person or direct contact with lesions of chickenpox or shingles) may benefit from treatment with antiviral drugs or injection antibodies against the varicella-zoster virus , Varig (VariZIG in Canada), which helps quickly to fight against the infection as appropriate.

People with a weakened immune system without a history of chickenpox, pregnant women with no history of chickenpox who are exposed to the virus, some premature babies, and newborns whose mothers have contracted chickenpox during the 5 days before or 2 days after delivery.