Sentinel surveillance of influenza and other respiratory viruses, Brazil, 2000–2010

Abstract

There are scanty data on the epidemiology of influenza and other respiratory viruses in South America and Brazil. The aim of this study was to summarize the data from the Brazilian surveillance system of influenza and other respiratory viruses and discuss the patterns of viral circulation. The system is based on detecting cases of influenza-like illness in sentinel sites and weekly collection of five nasopharyngeal secretions samples, which are processed in state public health laboratories for respiratory viruses by indirect immunofluorescence assay. Data from 2000 to 2010 were described over time, by region, gender, and age group, and an analysis of Spearman correlation was performed between monthly influenza detection and rainfall and temperature data in two state capitals with the highest number of positive samples, one from the northeast region (Maceió) and other from the southern region (Curitiba). There were 3,291,946 visits for influenza-like illness; of these, 37,120 had samples collected and 6421 tested positive: 1690 (26%) influenza A, 567 (9%) influenza B, 277 (4%) parainfluenza 1, 571 (9%) parainfluenza 2, 589 (9%) parainfluenza 3, 742 (12%) adenovirus, and 1985 (31%) respiratory syncytial virus. Overall, increased activity of respiratory syncytial virus was observed from March to June, preceding the peak of influenza activity, from May to August, but with regional differences. In Maceió, there was a weak correlation between temperature and influenza detection (ρ=0.05), but a moderate positive correlation between rainfall and influenza detection (ρ=0.36). In Curitiba, a high correlation was observed between the decrease in temperature and rainfall and the increase in influenza detection (ρ=-0.83 and -0.78 respectively). These data are important to guide public health control measures as the best time for influenza vaccination and use of antivirals.

Respiratory syncytial virus in Brazilian infants – Ten years, two cohorts

“…In the 2014 cohort, there was a higher incidence of AVB in April, more babies with a birth weight < 3000 g and gestational age < 37 weeks. Regarding the higher number of AVB cases in April 2014, the fact that both cohorts had higher number of cases occurred in April, May and June (a typical seasonality previously described) has to be taken into account [11,20,21]. This difference can be attributed to special weather conditions or a different pattern of virus circulation in 2014.…”

Exacerbation of asthma and airway infection: is the virus the villain?

“…As técnicas de amplificação de ácido nucleico (RT-PCR) são mais dispendiosas, porém mais sensíveis, sendo utilizadas em pesquisas e atualmente também utilizadas pelo MS para a identificação e genotipagem do vírus influenza. 38 Além disso, permitem identificar alguns vírus de significativa importância clínica e epidemiológica, como o rinovírus e o bocavírus, não identificado por imunofluorescência. 17,54 Quanto à forma de obtenção da amostra, vale ressaltar a questão controversa do swab nasofaríngeo na pesquisa viral.…”

“…Entretanto tal swab não é rotineiramente utilizado nos serviços e nas pesquisas em nosso meio. 38 No que se refere à relação entre a infecção viral e a exacerbação da asma, observamos ampla variação em relação aos métodos dos estudos que realizaram pesquisa de infecção viral em crianças asmáticas exacerbadas, por nós avaliados. Por exemplo, o tamanho da amostra variou entre os estudos de 58 a 1.052 casos, e a faixa etária, desde zero a 17 anos.…”

“…Estas revelam uma predominância dos vírus influenza e sincicial respiratório, com circulação ao longo de todo o ano, com picos para este último entre março e junho, e entre maio e agosto para o vírus influenza. 38 Não foram localizados dados referentes à circulação do rinovírus no nosso país.…”

Exacerbation of asthma and airway infection: is the virus the villain?

“…They showed a predominance of FLUV and hRSV, with circulation throughout the year, with peaks for the latter between March and June, and between May and August for FLUV. 38 No data were located concerning the movement of hRV in Brazil.…”