VZV47

Infection with VZV presents in two clinical forms: The proary infection;varicella(or chickenpox) is a generalized eruption, whereas the reactivation; zozter (or shingles) is localized. There is only one antigenic type of VZV.

Pathogenesis and clinical picture

1. Varicella (chickenpox) : The virus is thought to enter, by droplet infection, through the upper respiratory tract. After an incubation period about 2 weeks, the typical rash of varicella appears first on the trunk then spread to the face and limbs. The skin rash is initially macular and rapidly evolves through papules to clear vesicles. The vesicles change to pustules which dry to form scabs which heal without scar formation.

The patient is usually a child 4-10 years old. Disease usually runs a benig course. Some cases are complicated by secondary infection of skin, pneumonia or cerebellar ataxia. Pregnant women infected in the first half of pregnancy may pass infection to the foetus which at birth may show foetal varicella syndrome with high mortality rate.

2. Zoster (shingles): It results from reactivation of latent varicella infection in the neurons. The virus reaches the ganglion from the periphery by travelling along nerve axons or by blood during viraemic stage of varicella infection during childhood.

The disease usually occurs in older people and manifests as painful vesicular eruption, unilateral and confined to one dermatome usually thoracic or lumbar. The condotion may follow trauma to the spinal cord or may be complicate lymphomas, leikaemia or immuno supression.

Treatment

Acyclovir givenI.V is effective in the treatment of varicella and zoster. It is not used for all cases, but indicated in the following conditions:

1. Immunocompromized patients
2. Ophthalmic zoster to avoid corneal scarring
3. Varicella complicated by pneumonia
4. Neonatal infection

Prevention and control
1. Acyclovir and interferon are given to immune deficient children.
2.VZ immune globulin (VZIG) of high antibody titre should be given to contacts of cases to prevent development of disease.
3. Live attenuated varicella vaccine( Varivax) is given as one dose for children1-12 years of age.