RESUMO
The activity and circulation of influenza viruses in Argentina was studied during 2012 as part of the Argentinean Surveillance for Influenza and other Respiratory Viruses, in the context of Global Influenza Surveillance. The antigenicity and molecular characteristics of haemagglutinins (HA) of circulating influenza A and B viruses were analysed to assess the emergence of virus variants. Susceptibility to oseltamivir and zanamivir was evaluated by enzymatic assay and results were backed-up by sequencing of the neuraminidase (NA) genes. During the 2012 season, influenza virus circulation in Argentina was detected from weeks 24 to 51. The HA sequences of the studied A(H1N1)pdm09 subtype viruses segregated in a different genetic group compared to those identified during the 2009 pandemic, although they were still closely related antigenically to the vaccine virus A/California/07/2009. The HA sequences of the A(H3N2) viruses analysed fell into the A/Victoria/208/2009 clade, genetic group 3C. A mixed circulation of virus variants belonging to B/Victoria and B/Yamagata lineages was detected, with B/Victoria being dominant. All viruses tested were sensitive to oseltamivir and zanamivir except one. This isolate, an A(H1N1)pdm09 virus possessing the substitution NA-N295S, showed highly reduced inhibition by oseltamivir and reduced inhibition by zanamivir. Virological and epidemiological surveillance remains critical for detection of evolving influenza viruses.
Assuntos
Antivirais/farmacologia , Farmacorresistência Viral , Vírus da Influenza A/efeitos dos fármacos , Vírus da Influenza B/efeitos dos fármacos , Influenza Humana/epidemiologia , Vigilância da População , Argentina/epidemiologia , Hemaglutininas/genética , Hemaglutininas/metabolismo , Humanos , Vírus da Influenza A/genética , Vírus da Influenza A/imunologia , Vírus da Influenza A/fisiologia , Vírus da Influenza B/genética , Vírus da Influenza B/imunologia , Vírus da Influenza B/fisiologia , Influenza Humana/virologia , Neuraminidase/genética , Neuraminidase/metabolismo , Proteínas Virais/genética , Proteínas Virais/metabolismoRESUMO
During the influenza pandemic of 2009, the A(H1N1)pdm09, A/H3N2 seasonal and influenza B viruses were observed to be co-circulating with other respiratory viruses. To observe the epidemiological pattern of the influenza virus between May 2009-August 2011, 467 nasopharyngeal aspirates were collected from children less than five years of age in the city of Salvador. In addition, data on weather conditions were obtained. Indirect immunofluorescence, real-time transcription reverse polymerase chain reaction (RT-PCR), and sequencing assays were performed for influenza virus detection. Of all 467 samples, 34 (7%) specimens were positive for influenza A and of these, viral characterisation identified Flu A/H3N2 in 25/34 (74%) and A(H1N1)pdm09 in 9/34 (26%). Influenza B accounted for a small proportion (0.8%) and the other respiratory viruses for 27.2% (127/467). No deaths were registered and no pattern of seasonality or expected climatic conditions could be established. These observations are important for predicting the evolution of epidemics and in implementing future anti-pandemic measures.
Assuntos
Vírus da Influenza A Subtipo H1N1/isolamento & purificação , Vírus da Influenza A Subtipo H3N2/isolamento & purificação , Vírus da Influenza B/isolamento & purificação , Influenza Humana/epidemiologia , Estações do Ano , Tempo (Meteorologia) , Adenoviridae/isolamento & purificação , Brasil/epidemiologia , Pré-Escolar , Processos Climáticos , Coinfecção , Técnica Indireta de Fluorescência para Anticorpo , Humanos , Lactente , Recém-Nascido , Vírus da Influenza A Subtipo H1N1/fisiologia , Vírus da Influenza A Subtipo H3N2/fisiologia , Vírus da Influenza B/fisiologia , Influenza Humana/virologia , Líquido da Lavagem Nasal/virologia , Pandemias , Chuva/virologia , Vírus Sinciciais Respiratórios/isolamento & purificação , Respirovirus/isolamento & purificação , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência , Luz Solar , Carga ViralRESUMO
During the influenza pandemic of 2009, the A(H1N1)pdm09, A/H3N2 seasonal and influenza B viruses were observed to be co-circulating with other respiratory viruses. To observe the epidemiological pattern of the influenza virus between May 2009-August 2011, 467 nasopharyngeal aspirates were collected from children less than five years of age in the city of Salvador. In addition, data on weather conditions were obtained. Indirect immunofluorescence, real-time transcription reverse polymerase chain reaction (RT-PCR), and sequencing assays were performed for influenza virus detection. Of all 467 samples, 34 (7%) specimens were positive for influenza A and of these, viral characterisation identified Flu A/H3N2 in 25/34 (74%) and A(H1N1)pdm09 in 9/34 (26%). Influenza B accounted for a small proportion (0.8%) and the other respiratory viruses for 27.2% (127/467). No deaths were registered and no pattern of seasonality or expected climatic conditions could be established. These observations are important for predicting the evolution of epidemics and in implementing future anti-pandemic measures.
Assuntos
Pré-Escolar , Humanos , Lactente , Recém-Nascido , Vírus da Influenza A Subtipo H1N1/isolamento & purificação , /isolamento & purificação , Vírus da Influenza B/isolamento & purificação , Influenza Humana/epidemiologia , Estações do Ano , Tempo (Meteorologia) , Adenoviridae/isolamento & purificação , Brasil/epidemiologia , Processos Climáticos , Coinfecção , Técnica Indireta de Fluorescência para Anticorpo , Vírus da Influenza A Subtipo H1N1/fisiologia , /fisiologia , Vírus da Influenza B/fisiologia , Influenza Humana/virologia , Líquido da Lavagem Nasal/virologia , Pandemias , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Chuva/virologia , Vírus Sinciciais Respiratórios/isolamento & purificação , Respirovirus/isolamento & purificação , Análise de Sequência , Luz Solar , Carga ViralRESUMO
The trends of influenza infection in Suriname were assessed from February 2010 through February 2011. Testing of 393 patients with symptoms of acute respiratory infection (ARI) revealed 15.3% Influenza B and 18.6% could be identified as influenza A positive, consisting of 56% influenza A(H1N1)pdm09 and 44% seasonal A(H3N2). Influenza infection occurred throughout the year, and all three influenza types affected young children as the primary population. The annual incidence of A(H1N1)pdm09 was 6.88 per 100,000 inhabitants [CI] 4.87-9.45. The spread of influenza could neither be linked to tourist flow from the Netherlands nor to contact rates related to school schedules.