Seroprevalence and Risk Factors of Varicella-Zoster Among Children of Kashan- Center of Iran

Background: Varicella, the primary infection of varicella-zoster virus (VZV), is a highly contagious and vaccine preventable infectious disease. It can cause severe complications in neonates and adults. Herpes zoster results from VZV reactivation later in life. Objectives: This study was performed to determine the seroprevalence of VZV by evaluating the specific IgG antibody in 1-15 year-old children in Kashan. Patients and Methods: This cross-sectional study was carried out on 558, one through fifteen year-old children among health-care centers in Kashan city during 2011. IgG antibodies against VZV were measured in sera by enzyme-linked immunosorbent assay (ELISA). Results: In total, 27.6% of children were seropositive. The seroprevalence of varicella zoster antibodies increased by age (12.7% in 1-5 year-old, 34.4% in 6-10 year-old and 39.6% in 11-15 year-old children). There was no difference in seroprevalence of VZV according to sex and habitation zone. By using multivariate analysis, independent factors associated with seropositivity were the family size being greater than 4 (OR = 2.01, 95% CI 1.35 - 3.29 P = 0.001) and history of varicella (OR = 39.31, 95% CI 22.79-67.79 P < 0.001). The Negative predictive value of varicella history was 91.1% and slightly decreased by age. Conclusions: In this region, a significant proportion of children are susceptible to VZV, severe varicella and it's complications at older ages. It is recommended for varicella vaccine to be added to routine childhood vaccination programs and also to be injected to susceptible adolescents. Negative history of varicella would be a predictor of varicella antibody status in children and young adults.