Respiratory syncytial virus evaluation among asymptomatic and symptomatic subjects in a university hospital in Sao Paulo, Brazil, in the period of 2009-2013.

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.

Influenza virus prevalence in asymptomatic and symptomatic subjects during pandemic and postpandemic periods.

BACKGROUND: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

Influenza virus surveillance among young children in São Paulo, Brazil: the impact of vaccination.

This study assessed the presence of influenza virus among young children and the coverage of vaccination from 2010 to 2012 in São Paulo, Brazil. Our results demonstrated a lower rate of influenza detection and a predominance of influenza B. A decrease of coverage vaccination through the surveillance periods was observed.

Influenza virus surveillance among young children in São Paulo, Brazil: the impact of vaccination

This study assessed the presence of influenza virus among young children and the coverage of vaccination from 2010 to 2012 in São Paulo, Brazil. Our results demonstrated a lower rate of influenza detection and a predominance of influenza B. A decrease of coverage vaccination through the surveillance periods was observed.

H1N1: pandemia e perspectiva atual / H1N1: overview and perspectives

O vírus influenza de origem suína, A/California/04/2009 (H1N1), foi inicialmente detectado no México e determinou a pandemia de influenza de 2009. Em agosto de 2010, a Organização Mundial da Saúde (OMS) declarou o início da fase pós-pandêmica. As características dessa última pandemia foram marcadamente diferentes das anteriores. O vírus emergiu de rearranjos genéticos originários em hospedeiro mamífero não humano, demonstrou transmissibilidade interespécies e afetou a população humana de forma diferente dos vírus pandêmicos anteriores (1918, 1957 e 1968) com maior morbidade e mortalidade em crianças e adultos jovens. Atualmente, o vírus apresenta padrão sazonal da mesma forma que o influenza A H3N2 e o influenza B, mantendo, até o momento, o mesmo perfil de patogenicidade, espectro clínico e sensibilidade a antivirais. A cepa foi incluída na vacina sazonal trivalente anual recomendada, principalmente para proteção dos grupos de risco mais vulneráveis a complicações pelas diferentes cepas de influenza.

The swine origin influenza virus A/CALIFORNIA/04/2009 (H1N1) was first detected in Mexico and determined the 2009 influenza pandemic. In August 2010, World Health Organization (WHO) declared the beginning of the post-pandemic period. This last pandemic was distinctly different from previous ones. The virus emerged from genetic rearrangement in non-human mammalian host. Moreover, its inter-species transmission is fully reported. However, it affected human population differently from previous pandemic viruses (1918, 1957, 1968), with increased morbidity and mortality among children and young adults. Currently, the virus has a seasonal pattern in the same way as influenza A H3N2 and influenza B, maintaining the same pathogenicity profile, clinical spectrum and sensitivity to antiviral agents. The strain was included in the annual trivalent seasonal vaccine formulation, mainly for risk groups, which are more vulnerable to complications caused by different influenza strains.

Occurrence of influenza among patients hospitalized for suspicion of influenza A (H1N1) infection in 2010 at a sentinel hospital in São Paulo, Brazil.

In 2010, 96 patients suspected of being infected with the influenza A (H1N1) virus were hospitalized at the Hospital São Paulo, located in the city of São 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 São Paulo. The decrease in the number of hospitalizations for H1N1 infection in 2010 might be attributable to vaccination.

Casos confirmados de influenza em pacientes hospitalizados com suspeita de infecção por influenza A (H1N1) em 2010 em um hospital sentinela na cidade de São Paulo / Occurrence of influenza among patients hospitalized for suspicion of influenza A (H1N1) infection in 2010 at a sentinel hospital in São Paulo, Brazil

Em 2010, 96 pacientes com suspeita de infecção por influenza A (H1N1) foram hospitalizados no Hospital São Paulo, na cidade de São Paulo (SP). Desses, 4 pacientes (4,2 por cento) foram diagnosticados com influenza A - 3 com influenza A (H1N1) e 1 com influenza sazonal - e 2 pacientes (2,1 por cento) foram diagnosticados com influenza B. A maioria dos casos suspeitos (63,5 por cento) e metade dos casos positivos ocorreram em crianças. A segunda onda de influenza A (H1N1) foi mais fraca em São Paulo. A vacinação pode ter contribuído para a redução das internações devido a essa infecção em 2010.

In 2010, 96 patients suspected of being infected with the influenza A (H1N1) virus were hospitalized at the Hospital São Paulo, located in the city of São Paulo, Brazil. Of those 96 patients, 4 (4.2 percent) 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 percent) were found to be infected with influenza B virus. Most (63.5 percent) 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 São Paulo. The decrease in the number of hospitalizations for H1N1 infection in 2010 might be attributable to vaccination.