ChickenPox

Chickenpox is the common name for Varicella zoster, classically one of the childhood infectious diseases caught by and survived by almost every child.

Chickenpox is caused by the varicella-zoster virus (VZV), also known as human herpes virus 3 (HHV-3), one of the eight herpes viruses known to affect humans. It starts with conjunctival and catarrhal symptoms and then characteristic spots appearing in two or three waves, mainly on the body and head rather than the hands and becoming itchy raw pox (pocks), small open sores which heal mostly without scarring.

Chickenpox has a 10-14 day incubation period and is highly contagious through physical contact two days before symptoms appear. Following primary infection there is usually lifelong protective immunity from further episodes of chickenpox.

Chickenpox is rarely fatal (usually from varicella pneumonia), with pregnant women and those with a suppressed immune system being more at risk. Pregnant women not known to be immune and who come into contact with chickenpox may need urgent treatment as the virus can cause serious problems for the fetus. This is less of an issue after 20 weeks.

Later in life, viruses remaining dormant in the nerves can reactivate causing localised eruptions of shingles. This occurs particularly in people with compromised immune systems, such as the elderly, and perhaps even those suffering sunburn. Unlike chickenpox which normally fully settles, shingles may result in persisting post-herpetic neuralgia pain.

Signs and Symptoms

Chickenpox is a highly contagious disease that spreads from person to person by direct contact or through the air from an infected person's coughing or sneezing. Touching the fluid from a chickenpox blister can also spread the disease. A person with chickenpox is contagious from one to two days before the rash appears until all blisters have formed scabs. This may take five to 10 days. It takes from 10-21 days after contact with an infected person for someone to develop chickenpox.

The chickenpox lesions (blisters) start as a two to four millimeter red papule which develops an irregular outline (a rose petal). A thin-walled, clear vesicle (dew drop) develops on top of the area of redness. This "dew drop on a rose petal" lesion is very characteristic for chickenpox. After about eight to 12 hours the fluid in the vesicle gets cloudy and the vesicle breaks leaving a crust. The fluid is highly contagious, but once the lesion crusts over, it is not considered contagious. The crust usually falls off after seven days sometimes leaving a crater-like scar. Although one lesion goes through this complete cycle in about seven days, another hallmark of chickenpox is the fact that new lesions crop up every day for several days. Therefore, it may take about a week until new lesions stop appearing and existing lesions crust over. Children are not to be sent back to school until all lesions have crusted over.

Secondary infections, such as inflammation of the brain, can occur in immunocompromised individuals. This is more dangerous with shingles.

Chickenpox is highly contagious and is spread through the air when infected people cough or sneeze, or through physical contact with fluid from lesions on the skin. Zoster, also known as shingles, is a reactivation of chickenpox and may also be a source of the virus for susceptible children and adults. It is not necessary to have physical contact with the infected person for the disease to spread. Those infected can spread chickenpox before they know they have the disease - even before any rash develops. In fact, people with chickenpox can infect others from about two days before the rash develops until all the sores have crusted over, usually four to five days after the rash starts.

Chickenpox infection tends to be milder the younger a child is and symptomatic treatment, with a little sodium bicarbonate in baths or antihistamine medication to ease itching, and paracetamol (acetaminophen) to reduce fever, are widely used. Ibuprofen can also be used on advice of a doctor. However, aspirin or products containing aspirin must not be given to children with chickenpox (or any fever-causing illness), as this risks causing the serious and potentially fatal Reye's Syndrome.

There is no evidence to support the effectiveness of topical application of calamine lotion, a topical barrier preparation containing zinc oxide in spite of its wide usage and excellent safety profile.

It is important to maintain good hygiene and daily cleaning of skin with warm water to avoid secondary bacterial infection. Infection in otherwise healthy adults tends to be more severe and active; treatment with antiviral drugs (e.g. acyclovir) is generally advised. Patients of any age with depressed immune systems or extensive eczema are at risk of more severe disease and should also be treated with antiviral medication. In the U.S., 55 percent of chickenpox deaths are in the over-20 age group, even though they are a tiny fraction of the cases.

info : wikipedia