Sero-Prevalence of Antibodies against Varicella Zoster Virus in Children under Seven-Years Old in 2012 in Tehran, Iran

BACKGROUND Varicella zoster virus (VZV) is a member of herpes family viruses, which causes varicella (chickenpox) after primary infection and herpes zoster (shingles) because of latent virus reactivation from dorsal root ganglia. Generally, prevalence of varicella antibodies increases with age. We aimed to compare the prevalence of anti-VZV antibody in children under seven years old, in order to obtain a preliminarily picture of general presence of these antibodies to design an immunization plan. METHODS In this cross-sectional study, performed from September 2011 to September 2012 in Tehran, Iran, 267 serum samples including sera from 7 month old infants, n= 87; 18 month old children, n= 86; and 6 year old children, n= 94 were assessed for the presence of specific IgG antibodies against VZV, using ELISA technique. RESULTS 4.6% of 7 month, 12.8% of 18 month and 21.3% of 6-year-old children were seropositive. No relation was found between demographic variables (e.g. age and birth weight) and seropositivity in these age groups. VZV antibodies increased with age. Serum levels of varicella antibodies were elevated in 18 months old compared to 7 months old children, significantly (P < 0.001). CONCLUSION In view of the significant elevation of VZV antibodies in children from 7 months to 18 months of age and rate of seronegative children, our results support the necessity of varicella immunization between 7 and 18 months of age in order to prevent viral infection.