Title : Viral pathogens associated with acute lower respiratory tract infections in Bulgaria
Acute lower respiratory tract infections are a major cause of morbidity and hospital admissions. This study aimed to determine the viral etiology of these infections among the patients of different age groups in Bulgaria during the period October 2016-September 2019. Nasopharyngeal specimens were collected from patients with bronchiolitis, pneumonia, and exacerbation of chronical respiratory diseases (asthma, COPD). The viral etiology was determined by individual Real-Time PCR assays against 12 respiratory viruses. Of the 644 patients examined, 476 (73.9%) were positive for at least one virus. Co-infections with two and three viruses were found in 81 (17%) of the infected patients. Among the 532 children younger than 5 years, respiratory-syncytial virus (RSV) was the predominant pathogen (37.4%), followed by rhinoviruses (14.1%), bocaviruses (8.8%), human metapneumovirus (7%), adenoviruses (6.8%), influenza A(H3N2) (4.7%) and influenza A(H1N1)pdm09 (3.8%) viruses. RSV-B were more prevalent than RSV-A throughout the study period. At least one respiratory virus was identified in 82.9% and 67.2% of the children with bronchiolitis and pneumonia, respectively. Among the patients >5 years, influenza A(H1N1)pdm09 virus was the most frequently detected (16.5%), followed by RSV (8.8%) and influenza A(H3N2) (7.8%). Diagnostic testing for respiratory viruses using molecular methods may lead to the reduced use of antibiotics and may assist in measures to control infection.