Varicella Zoster Virus (VZV)

VZV infects the nerves causing a wide variety of symptoms and two clinically distinct forms of disease. Primary infection results in chickenpox and recurrent infections leads to herpes zoster (shingles). Symptoms of VZV are exhibited between 10 and 21 days after infection. The main symptom is a rash that turns into open lesions which crust over. It is spread through the airborne route primarily from the skin vesicles. The immunologic mechanism that controls latency of VZV is not well understood, however factors associated with recurrent disease include aging, immunosuppression, intrauterine exposure to VZV, and having had varicella at a young age (younger than 18 months). Infection with VZV is generally mild and self-limited, but it may be associated with complications, especially in adults or children under 1-year old. Secondary bacterial infections of skin lesions with Staphylococcus or Streptococcus are the most common cause (5% of cases) of hospitalization and invasive group A streptococci can lead to serious illness or death. Other complications include secondary pneumonia (bacterial or viral), aseptic meningitis, encephalitis, myocarditis and arthritis. A rarer complication is Reye’s syndrome and occurs almost exclusively in children who take aspirin during the acute illness. Routine vaccination against VZV is performed in the United States and Japan, however most countries still do not vaccinate. It is now available as a quadrivalent measles-mumps-rubella-varicella (MMRV) vaccine and it is gaining wider acceptance globally. The VZV vaccine is on the World Health Organization’s (WHO) List of Essential Medicines, a list of the most important medications needed in a basic health system.

Congenital Infection

Primary maternal varicella infection in the first 20 weeks of gestation is associated with a variety of abnormalities in the newborn collectively known as congenital varicella syndrome. The range and severity of associated symptoms and physical findings may vary greatly from case to case depending upon when the maternal varicella zoster infection occurred during fetal development. In general, newborns with congenital VZV have a low birth weight, distinctive skin abnormalities, and brain malformations.