Comparison of the dynamics and correlates of transmission of Herpes Simplex Virus-1 (HSV-1) and Varicella-Zoster Virus (VZV) in a sample of the Israeli population.

Herpes simplex virus types-1 (HSV-1) and Varicella-zoster virus (VZV) are herpes viruses that share many characteristics. However, HSV-1 spreads by close contact while VZV spreads mainly by the airborne route. In this study we compared the dynamics and correlates of transmission of these viruses in the same population. In 2000-2001, 1555 sera from an age-stratified general population sample were tested using commercial ELISA kits to measure type-specific HSV-1 and varicella IgG antibodies. The VZV seroprevalence increased rapidly with age reaching 50% seropositivity by the age of 3 years, while HSV-1 reached 50% seropositivity at the age of 14 years. The highest VZV force of infection was in the 3.5-5.5-year age group followed by the 5.5-10.5 years age group, while for HSV-1 the age specific force of infection was substantially lower and stable over the various age groups. Multivariate analysis revealed that HSV-1 seroprevalence was significantly, independently associated with age, country of birth, country of origin, ethnicity, socio-economic status and VZV sero-status. Only age, country of origin and HSV-1 sero-status were found to be associated with VZV seropositivity. In developed countries such as Israel the transmission of VZV is much quicker and less dependent on socioeconomic status as compared with HSV-1.