Influenza and other respiratory viruses 2017 10 27() doi 10.1111/irv.12518
RSV is recognized as an important cause of respiratory tract infections. Immunocompromised patients, health care workers (HCW) and children contacts are at increased risk of acquiring the infection. However, the impact of asymptomatic infection in transmission has not been well studied. This study evaluated the frequency and viral load (VL) of RSV in nasal swab samples of individuals with different risk factors for acquiring infection in a university hospital in Sao Paulo, Brazil. We included 196 symptomatic children and their 192 asymptomatic caregivers, 70 symptomatic and 95 asymptomatic HCW, 43 samples from symptomatic HIV positive outpatients and 100 samples of asymptomatic HIV patients in the period of 2009 to 2013. RSV infection was detected in 10.1% (70/696) of samples, 4.4% (17/387) of asymptomatic patients and 17.1% (53/309) from symptomatic patients. (p< 0.0001). The VL of symptomatic patients (4.7 log copies/mL) was significantly higher compared to asymptomatic patients (2.3 log copies/mL). RSV detection among asymptomatic caregivers (6.8%; 13/192) was significantly higher compared to other asymptomatic adults, HIV and HCWS (2.0%; 4/195; p = 0.0252). A close contact with an infected child at home was an important risk to RSV acquisition [OR 22.6 (95% CI 4.8 to 106.7)]. Children who possibly transmitted the virus to their asymptomatic contacts had significantly higher viral load than children who probably did not transmit (p < 0.0001). This article is protected by copyright. All rights reserved.