Seroprevalence and Risk Factors of Varicella Zoster Infection in Iranian Adolescents: A Multilevel Analysis; The CASPIAN-III Study.

Shervin Ghaffari Hoseini,Amir Kasaeian,Roya Kelishadi,Mohammad Esmaeil Motlagh,Gelayol Ardalan,Majid Yaran,Omid Safari,Seyed Naseredin Mostafavi,Ramin Heshmat,Behrooz Ataei,Mostafa Qorbani,Ilhem Messaoudi

doi:10.1371/journal.pone.0158398

Abstract

The objective of this study was to evaluate the varicella zoster virus (VZV) immunity in Iranian adolescents. It was conducted as a primary study for vaccine implementation, and to investigate the association of climatic and socioeconomic factors with the epidemiology of this infection. In this cross- sectional study, anti VZV antibodies were measured in serum samples obtained in a national school-based health survey (CASPIAN- III). Association of demographic, socio-economic, and climate of the living region with the frequency of VZV was investigated by multivariate multilevel analysis. Overall, sera of 2753 individuals aged 10–18 were tested for VZV antibodies, from those 87.4% were positive. The prevalence was statistically different in four socio-geographic regions (P<0.001), varying between 85.24% in West region (mostly mountainous areas with cold climate) to 94.59% in Southeast region (subtropical climate). Among variables studied, only age and mean daily temperature of the living area were positively associated with the VZV seroprevalence. Our findings show that most Iranians develop immunity to VZV before the age of 10, but a substantial proportion of them are yet susceptible to the infection. Therefore, it seems that the best strategy to reduce the burden of the disease is to vaccinate high- risk adults, i.e. those without a history of varicella infection. The regional temperature might be the only determinant of VZV epidemiology in Iran.

Highlights

Chickenpox is an extremely infectious viral disease with universal distribution, which is caused by Varicella zoster virus (VZV)
Our findings show that most Iranians develop immunity to varicella zoster virus (VZV) before the age of 10, but a substantial proportion of them are yet susceptible to the infection
Significant difference was documented in the VZV seroprevalence according to the region and age groups, but the ratios were not so divergent; the findings indicate that at age of 10, about 20% of Iranian children are susceptible to this infection, and at age of 18, the susceptibility declines to less than 10% in all four socio-geographic regions

Summary

Introduction

Chickenpox (varicella) is an extremely infectious viral disease with universal distribution, which is caused by Varicella zoster virus (VZV). Life threatening events including pneumonia, necrotizing fasciitis, encephalitis, septicemia, and disseminated varicella rarely may be observed, as well [1]. After primary VZV infection, the virus becomes dormant in sensory nerve ganglia. Following subsequent reactivation, this virus may produce zoster (shingles), a pruritic vesicular exanthema with local distribution in a dermatome. Zoster may occasionally cause permanent neurological impairments including postherpetic neuralgia, cranial nerve palsies, and visual defects [1]. Complications and mortality of VZV infection are more commonly detected in immuno-deficient patients, and are more frequently observed in adults than in the pediatric population [3]

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