Etiology, Seasonality, and Clinical Features of Viral Respiratory Tract Infections in Children Hospitalized With Acute Bronchiolitis: A Single-Center Study

Gökçe, Sule; Kurugöl, Zafer; Koturoglu, Güldane; Çiçek, Candan; Aslan, Asli

The findings are in agreement with the results of several studies previously reported, in which RSV was diagnosed in 50% to 80% of infants admitted to hospital with acute bronchiolitis. [21] [22] [23] [24] [25] [26] RSV was the most common virus identified in 127 infants (40.1%) in our study. Stempel et al 26 showed that RSV incidence was 77%, and Antunes et al 27 found this as 58.1% in the RSV epidemic season. In our study, RSV was the most frequently identified respiratory virus, accounting for 40.1% of all respiratory viruses. In addition, 24.6% of the infants in our study were positive for rhinovirus, followed by influenza virus (8.8%), human metapneumovirus (8.5%), adenovirus (7.2%), human bocavirus (6.3%), parainfluenza virus (5.6%), and human coronavirus (3.1%). Human rhinoviruses are the most common human respiratory pathogens and are responsible for most upper respiratory infections (eg, common cold). They may also cause severe lower respiratory tract infections, including pneumonia and bronchiolitis. 28 Additionally, human rhinoviruses are known as a major pathogen for asthma exacerbations in children and adults. Recently, some studies have shown rhinoviruses to be the second most commonly seen pathogen for AB. A study conducted in the United States found a prevalence of 25.6% for rhinovirus, 25 similar to our study. However, other studies reported a lower incidence rate of human rhinoviruses in acute bronchiolitis. 24, 29, 30 Our study showed that the respiratory viral agents exhibited seasonal patterns with the number of RSV and rhinovirus cases peaking in the winter season similar to that already published in previous studies. 31 It has been reported that the seasonal distribution of respiratory agents may occur due to meteorological conditions, spreading of infectious pathogens, and pathogen transmission by the host behavior due to different meteorological conditions. 32, 33 Another important theory on pathogen activity is total sunshine exposure. It is hypothesized that ultraviolet light radiation could affect the spread of RSV by inactivating it. 33, 34 The city of Izmir in Turkey, located in the west, has Mediterranean climate in which summers are hot and dry and winters are warm and rainy. This climatic feature could explain the seasonal pattern of respiratory viruses in our study.