Viral etiology of acute respiratory infections among children under 5 years of age in Bulgaria, during the 2013/2014 and 2014/2015 seasons

PURPOSE: A wide range of different viruses cause respiratory tract diseases of varying severity. This study aims to determinate the contribution of nine different viral pathogens in cases of acute respiratory infections (ARI) in children aged less than 5 years, during the 2013/2014 and 2014/2015 winter seasons in Bulgaria. METHODS: A total of 412 nasopharyngeal swabs of children under the age of 5 were tested. Children were either outpatient, or hospitalized for influenza-like illness. The clinical samples were tested for Orthomyxoviruses (influenza A/B), Paramyxoviruses (respiratory-syncytial virus – RSV; human metapneumovirus – HMPV; human parainfluenza viruses – HPIV, type 1/2/3) and human rhinoviruses (HRV) using Real Time RT-PCR reactions based on specific primers/probe. RESULTS: Virus infections were confirmed in 258 (62.6%) samples. In 107 (26%) of samples influenza viruses were detected. All of the 306 influenza virus negative patients were analyzed for Paramyxoand Rhinoviruses. Detection rate for RSV, HMPV, HPIV1/2/3 and HRV was 19%, 5.9%, 2%, 1.3%, 3.3% and 14.1%, respectively. CONCLUSION: The present study is the first one in Bulgaria which analyzes the participation of nine different viral pathogens in the etiology of ARI among children below the age of 5 years. The study reveals the leading role of influenza viruses, RSV and rhinoviruses in the development of serious respiratory diseases in early childhood.