Varicella (Chickenpox)

The primary varicella-zoster virus infection, is primarily a childhood disease in non-vaccinated population.

Chickenpox, is a highly contagious skin disease caused by the varicella-zoster virus (VZV).

Chickenpox is characterized by pruritic blister-like rash which may cover entire body, affecting all age groups.

Rates of chickenpox are higher in countries which lack adequate immunization programs. 

Characterized by a vesicular rash which is frequently accompanied by fever and malaise.

Usually a mild to moderate illness but can be complicated with pneumonia, CNS involvement, secondary bacterial infections, and rarely death.

Highly infectious with attack rates among contacts from 61-100% of susceptible individuals.

Worldwide infection and is endemic in most populations.

During primary infection genes are expressed sequentially with production of groups of non-structural and structural proteins with the latter forming a capsid surrounding the DNA core a tegument and a lipid containing envelope.

Envelope is composed of glycoproteins that are important in the disease pathogenesis.

After infection of the cell the varicella-zoster virus replicates in the nucleus with incorporation of DNA into preformed capsids which exit the nucleus by a first budding event at the inner nuclear membrane.

Following primary infection the virus persists in sensory nerve ganglia of the dorsal root with latent infection of neuronal cells.

Reactivation of virus years later can spread along a dermatome to cause herpes zoster manifested by a painful localized vesicular rash.

Since 1995 the incidence has declined as much as 90% as a result of the introduction of the varicella vaccine.

Since the introduction of the varicella vaccine the mortality rate has decreased by 66%.

The major reductions in the incidence and mortality rates with the introduction of the varicella vaccine is among children ages 1-4 years.

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