Ambispective epidemiological observational study of varicella-zoster virus infection: An 18 year-single-center Bulgarian experience.

Background: Varicella (chickenpox) and herpes zoster (shingles) are outcomes of varicella-zoster virus (VZV) infection, and understanding their incidence trends is vital for public health planning.

Aim: To conduct an ambispective epidemiological study by analyzing the main epidemiological characteristics of VZV infection during an 18 year-period (2000-2018).

Methods: We used descriptive and epidemiological methods to characterize chickenpox in Bulgaria, the city of Plovdiv and the region for a period of 18 years (2000-2018).

Results: The average incidence of varicella-zoster infection for the period 2000-2018 in the Plovdiv region was estimated at 449.58‰. The highest relative share of the infection was assessed in the month of January at 13.6%, and the lowest in the months of August and September at 2.9% (both months). The age group most affected by the infection was 1-4 years, followed by 5-9 years. This corresponds to the so-called "pro-epidemic population" - a phenomenon typical for airborne infections, confirming their mass impact on the perpetuation of VZV infection.

Conclusion: Our findings reveal significant insights into VZV epidemiology, including age-specific incidence rates, clinical manifestations, and vaccination impact. This comprehensive analysis contributes to the broader understanding of VZV infection dynamics and may inform evidence-based preventive measures.