Viral pathogens associated with acute lower respiratory tract infections in children younger than 5 years of age in Bulgaria
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Acute lower respiratory infections (ALRIs) are a leading cause of morbidity and hospital admissions in children. This study aimed to determine the viral etiology of these infections in children aged < 5 years during three successive epidemic seasons in Bulgaria. Nasopharyngeal and throat specimens were collected from children with bronchiolitis and pneumonia during the 2015/2016, 2016/2017, and 2017/2018 seasons. The viral etiology was determined by individual real-time PCR assays against 11 respiratory viruses. Of the 515 children examined, 402 (78.1%) were positive for at least one virus. Co-infections with two and three viruses were found in 64 (15.9%) of the infected children. Respiratory syncytial virus (RSV) was the predominant pathogen (37.5%), followed by rhinoviruses (13.8%), metapneumovirus (9.1%), adenoviruses (7%), bocaviruses (7%), influenza A(H1N1)pdm09 (4.9%), A(H3N2) (4.3%), type B (4.1%), and parainfluenza viruses 1/2/3 (2.9%). RSV-B were more prevalent than RSV-A during the three seasons. At least one respiratory virus was identified in 82.6% and 70.1% of the children with bronchiolitis and pneumonia, respectively. Respiratory viruses, especially RSV, are principal pathogens of ALRIs in children aged < 5 years. Diagnostic testing for respiratory viruses using molecular methods may lead to the reduced use of antibiotics and may assist in measures to control infection.
KeywordsAcute lower respiratory infections Bronchiolitis Pneumonia Viral infection
NK conceptualized and designed the study; ITz, SM, SV, and II were responsible for patient enrollment, assessment, and selection; NK, SA, ITr, IG, and SV performed the experiments; NK, ITr, ITz, SM, and II analyzed the work results; NK wrote the manuscript; TT and PP reviewed the final manuscript. All authors read and approved the final manuscript.
This work was financially supported by the National Science Fund (Project No DH 13-15/20.12.2017) and the Ministry of Health (National Plan of Republic of Bulgaria for Pandemic Influenza Preparedness).
Compliance with ethical standards
This study was carried out in accordance with The Code of Ethics of the World Medical Association (Declaration of Helsinki) for experiments involving humans http://www.healthscience.net/resources/declaration-of-helsinki.
Conflict of interest
The authors declare that they have no conflicts of interest relevant.
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