Search

Background The respiratory syncytial virus (RSV) is recognized as an important cause of respiratory tract infections. Immunocompromised patients, healthcare workers (HCWs) and children contacts are at increased risk of acquiring the infection. However, the impact of asymptomatic infection in transmission has not been well studied. Objectives: 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. Methods We included 196 symptomatic children and their 192 asymptomatic caregivers, 70 symptomatic and 95 asymptomatic HCWs, 43 samples from symptomatic HIV‐positive outpatients, and 100 samples of asymptomatic HIV patients in the period of 2009‐2013. Results 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 < .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 = .0252). A close contact with an infected child at home was an important risk to RSV acquisition [OR 22.6 (95% CI 4.8‐106.7)]. Children who possibly transmitted the virus to their asymptomatic contacts had significantly higher viral load than children who probably did not transmit (P < .0001). Conclusions According to our results, it is important to know if people circulating inside the hospital have close contact with acute respiratory infected children.

In 2009, Influenza A(H1N1)pdm09 had a major effect on global health, causing thousands of deaths. However, the results of asymptomatic infection in transmission has not been well studied. We analyzed asymptomatic influenza infection in individuals with different risk factors for acquiring influenza in a university hospital.Respiratory samples from 100 children with respiratory symptoms, their asymptomatic caregivers, 100 asymptomatic HIV-infected patients, and 100 health care workers collected during 2009-2011 were tested for influenza by real time real-time polymerase chain reaction.Influenza infection rate in symptomatic children was 44% and in asymptomatic adults it was 8.3% (P .01). Children older than age 5 years had a 3.4 times greater chance of being infected during influenza season than younger children. Among the asymptomatic group, influenza was more frequent in caregivers (14%; P = .032) and a higher rate (31.8%) was observed if a child was infected during the 2009 pandemic. Contact with an infected child was an important risk factor for influenza acquisition (odds ratio, 3.8; 95% confidence interval, 1.1-13.2) among caregivers. The mean cluster of differentiation 4 T-cell count of HIV-positive patients infected with influenza was not statistically different from uninfected patients (P = .29).Asymptomatic household contacts of symptomatic children may play an important role in community transmission and a more proactive intervention should be considered during future pandemics.

In 2010, 96 patients suspected of being infected with the influenza A (H1N1) virus were hospitalized at the Hospital Sao Paulo, located in the city of Sao Paulo, Brazil. Of those 96 patients, 4 (4.2%) were found to be infected with influenza A virus-3 with influenza A (H1N1) and 1 with seasonal influenza A-and 2 patients (2.1%) were found to be infected with influenza B virus. Most (63.5%) of the suspected cases occurred in children, as did half of the positive cases. The second wave of influenza A (H1N1) infection was weaker in Sao Paulo. The decrease in the number of hospitalizations for H1N1 infection in 2010 might be attributable to vaccination.

O virus influenza de origem suina, A/California/04/2009 (H1N1), foi inicialmente detectado no Mexico e determinou a pandemia de influenza de 2009. Em agosto de 2010, a Organizacao Mundial da Saude (OMS) declarou o inicio da fase pos-pandemica. As caracteristicas dessa ultima pandemia foram marcadamente diferentes das anteriores. O virus emergiu de rearranjos geneticos originarios em hospedeiro mamifero nao humano, demonstrou transmissibilidade interespecies e afetou a populacao humana de forma diferente dos virus pandemicos anteriores (1918, 1957 e 1968) com maior morbidade e mortalidade em criancas e adultos jovens. Atualmente, o virus apresenta padrao sazonal da mesma forma que o influenza A H3N2 e o influenza B, mantendo, ate o momento, o mesmo perfil de patogenicidade, espectro clinico e sensibilidade a antivirais. A cepa foi incluida na vacina sazonal trivalente anual recomendada, principalmente para protecao dos grupos de risco mais vulneraveis a complicacoes pelas diferentes cepas de influenza.