Comparative analysis of Respiratory Syncytial Virus frequency rates and viral load in different patient cohorts in a university hospital in Sao Paulo, Brazil, over an eight-year period (2005-2013)

Abstract

AbstractRespiratory Syncytial Virus (RSV) poses a global health concern, particularly in young children, the elderly, and those immunosuppressed. RSV viral load is essential for understanding transmission, disease severity, prevention, and treatment. This retrospective study aimed to analyze the frequency rates and viral loads of RSV infections in different patient cohorts and age groups over an eight-year period in a university hospital in São Paulo, Brazil. This study analyzed 1380 immunocompetent (IC) and immunosuppressed (IS) patients with acute respiratory tract infections. IC included patients suspected of having severe acute respiratory syndrome caused by influenza A (H1N1)pdm09 virus (SARS H1N1), chronic heart disease (HD), and those receiving primary care service (PC). The IS comprised transplant patients and individuals with human immunodeficiency virus (HIV) infection. Respiratory samples were collected between 2005 and 2013. RSV detection and quantification were performed by RT-qPCR. Viral load was expressed as Log10 copies of RNA/mL. The overall RSV infection rate was 17.3%, with higher rates in children (23.9%) than in adults (12.9%), particularly in children under two years of age (28.2%). Children in the SARS H1N1 and PC subgroups had higher infection rates (16.4% and 34.9%, respectively), with the highest rate in PC children aged 1 to <2 years (45.45%). Adults with HD had a significantly higher frequency rate (27.83%) than those in the SARS H1N1 (2.65%) and IS (15.16%) subgroups. The RSV viral load ranged from 2.43 to 10.15 Log10 RNA copies/mL (mean ±SD = 5.82 ± 2.19). Hospitalized patients had significantly higher viral loads (7.34 ± 1.9) than outpatients (4.38 ± 1.89). Elderly bone marrow transplant patients also had significantly higher viral loads (7.57 ± 2.41) than younger adults (5.12 ± 1.87). This study provides insights into the patterns and impacts of RSV infection in different patient cohorts in Brazil, contributing to developing effective prevention, treatment, and control strategies. Further investigations are needed to understand the susceptibility and risk factors associated with RSV infection.