What are the clinical features of herpes
zoster in immunocompromised
children ?




Herpes zoster causes a disseminated infection in immunosuppressed children. Usually, two to three days after the appearance of localized lesions, vesicles appear in other areas of the trunk and extremities. The appearance of remote lesion may continue for up to 2 weeks after that. There may be visceral involvement as well, including varicella pneumonitis, hepatitis and meningoencephalitis. Certain categories of immunocompromised children may suffer from chronic herpes zoster. Complications such as VZV retinitis, acute retinal necrosis and chronic progressive encephalitis have been reported.

What treatment is offered to otherwise healthy children with VZV infection?



Symptomatic treatment is the mainstay of therapy in immunocompetent individuals suffering from varicella infection. Pruritus can be managed by application of a drying lotion such as calamine or occasionally anti-histaminic preparations may be required for relieving itching. Aluminum acetate or soaks with burrow solution can be both soothing and cleansing in patients with herpes zoster. The fingernails should be trimmed to reduce the damage done by scratching. Daily bathing must be advised to decrease the probability of secondary skin infections. One should avoid using aspirin for treating fever in these children. Administration of aspirin to children with varicella is postulated to cause Reye's syndrome.

Use of systemic antiviral therapy is usual not necessary, although oral acyclovir has been used in the treatment of both chickenpox and herpes zoster in normal children. Such a therapy shortens the duration of lesion formation by about one day, reduces the total number of new lesion by about 25% and improves constitutional symptoms in one-third of patients. The American Academy of Pediatrics recommends therapy of adolescents and high-risk groups such as children with bronchopulmonary dysplasia within 24 hours of onset of disease. Oral acyclovir therapy of herpes zoster in the normal host accelerates cutaneous healing and reduce acute neuritis. Its effect on post-herpetic neuralgia is marginal, if any.

When does one use parenteral antiviral therapy in the management of chickenpox and herpes zoster ?



Parenteral anti-viral therapy is indicated for treatment of varicella infections (chickenpox as well as herpes zoster ) in immunocompromised patients. They should also be used in immunocompetent individuals when visceral complications such as varicella pneumonitis appear. Vidarabine has proven efficacy in treating varicella infections but it has been replaced by acyclovir . Acyclovir is not only potent but has fewer side-effects than vidarabine and has a high degree of selectivity for the inhibition of VZV replication.

What are the ways of preventing varicella ?


Varicella infection can be prevented by :

1. avoiding contact with cases of varicella,
2. providing passive immunization against varicella e.g. varicella zoster immune globulin,
3. administering vaccination against

What type of vaccine is available against varicella ?


A live-attenuated varicella viral vaccine is available for protecting children, adolescents and adults from varicella vaccine. An attenuated Oka strain is used in the vaccine.

Is it true that the varicella vaccine in extremely sensitive to temperature changes ?



Varicella vaccine that was initially introduced was highly sensitive to temperature changes. It required to be stored at -20 degree Celsius like most other vaccines. At these temperatures, the vaccine has a shelf-life of 2 years.

How effective is varicella vaccine in children, adolescents and adults?



Varicella vaccine is highly immunogenic. Seroconversion rates at 6 weeks following complete immunization in adults and children are as high as 92-98%. Its clinical efficacy has been studies extensively. Studies have shown that it provides protection from classical chickenpox to the extent of 100%

What is the dosage schedule for administration of varicella vaccine?


The varicella vaccine has been cleared for use in children over the age of 12 months. Children up to the age of 12 years require only one dose, which has to be administered subcutaneously. In contrast, individuals above the age of 12 years are advised two doses of the vaccine, which are administered 6-10 weeks apart.

Can varicella vaccine be administered simultaneously with other vaccines?



Varicella vaccine can be administered simultaneously with other immunizing agents such as polio vaccine and vaccine against measles, mumps, rubella, hepatitis-A, hepatitis-B, and H.influenzae type B. Such an administration does not interfere with immunogenicity of these vaccines nor does it increase the incidence or severity of complications. However in such situations, the injections should be given at different sites and the different vaccine preparations should not be mixed together.

What are the contraindications to the use of varicella vaccine ?


Being a live-viral vaccine, its use is contraindicated during pregnancy. The vaccine contains neomycin and hence history of systemic pre-sensitivity to neomycin is a definite contra-indication. If a child's total lymphocyte count is less then 1200/mm3 or if there is evidence of lack of cellular immune competence, varicella vaccine should not be administered. Presence of acute febrile illness in healthy subjects , the presence of a minor infection is not a contra-indication for vaccination.

What precautions would you take while immunizing a woman of the child-bearing age group ?



Pregnancy being an absolute contra-indication to the use of varicella vaccine, one must ensure that the woman is not pregnant. The lady should be advised to avoid pregnancy for next 3 months after vaccination.