Considerações metodológicas na interpretação do rastreamento sorológico da hepatite B em doadores de sangue

Between October 1988 and February 1989, 1,033 voluntary first-time blood donors were screened for hepatitis B infection in five blood banks in Goiânia, Central Brazil. The survey was part of a major study designed to estimate seroprevalence of HBsAg and anti-HBs and to discuss methodological issues related to prevalence estimation based on data from blood banks. Donors were interviewed and blood samples were collected and tested for HBsAg and anti-HBs by ELISA tests. Prevalences of 1.9% and 10.9% were obtained for HBsAg and anti-HBs, respectively, and no statistical difference was found between the sexes. Prevalence of anti-HBs increased with age (X² for trend = 7.9 p = 0.004). The positive predictive value and sensitivity of history of jaundice or hepatitis reported in the interview in detecting seropositives were 13.6% and 2.2%, respectively. The methodological issues, including internal and external validity of HBV prevalence estimated among blood donors are discussed. The potential usefulness of blood banks as a source of morbidity information for surveillance for Hepatitis B virus infection is stressed.Trata-se de parte de uma pesquisa sobre a soroprevalência e fatores de risco para as doenças infecciosas triadas pelos bancos de sangue, com o objetivo de discutir as implicações metodológicas na interpretação dos estudos seccionais realizados em bancos de sangue para estimativa da prevalência populacional para a infecção pelo Virus da Hepatite B (VHB). De outubro de 1988 a fevereiro de 1989, 1.033 primodoadores de sangue, de 5 dos 8 bancos de sangue da cidade de Goiânia - GO, Brasil, foram entrevistados. Uma amostra de sangue foi coletada para detecção dos marcadores sorológicos AgHBs e anti-HBs pela técnica de ELISA. Foram obtidas taxas de soroprevalência de 1,9% e 10,9% para AgHBs e anti-HBs, respectivamente. Não houve diferença estatisticamente significante na prevalência de AgHBs em diferentes grupos etários e sexo. Foi observado o aumento significante de anticorpos anti-HBs com a idade (X² para tendência = 7,9 p = 0, 004). O valor preditivo positivo e a sensibilidade da história de icterícia ou hepatite na anamnese em detectar soropositivos mostraram-se baixos, 13,6% e 2,2%, respectivamente. Foram discutidas a validade interna e externa e as limitações na extrapolação destas estimativas levando-se em consideração as características de distribuição etária e sexo da população, a "voluntariedade", um possível "efeito doador saudável" e a representatividade dos grupos de risco para infecção pelo VHB entre os doadores de sangue

Detection of calicivirus from fecal samples from children with acute gastroenteritis in the West Central region of Brazil

The objective of this study was to describe the circulation of caliciviruses in the West Central region of Brazil and its correlation with children's gender and age, as well as with the year and months of the sample collection. Reverse transcriptase-polymerase chain reaction was performed to detect the human calicivirus genome in 1006 fecal samples that were collected in Goiânia (n = 696) and Brasília (n = 310). Viral RNA was detected in 8.6% of the samples. No significant difference in viral prevalence was found regarding gender, age or year of the sample. However, it was observed that in Goiânia, there is a higher incidence of caliciviruses from September to March. The analysis employing three primer pairs demonstrated that the Ni/E3 or JV12/13 primer pairs, which detect norovirus (NoV), detected 41 positive samples while the 289/290 primer pair, which detects NoV or sapovirus, detected the remaining 46 samples. Calicivirus circulates in the West Central region of Brazil and for better detection of this virus it is important to use more than one primer pair. Also, we conclude that the seasonality presented by this virus is related to higher humidity in the period

Asthma exacerbations in a subtropical area and the role of respiratory viruses:a cross-sectional study

Background: Multiple factors are involved in asthma exacerbations, including environmental exposure and viral infections. We aimed to assess the association between severe asthma exacerbations, acute respiratory viral infections and other potential risk factors. Methods: Asthmatic children aged 4-14 years were enrolled for a period of 12 months and divided into two groups: those with exacerbated asthma (group 1) and non-exacerbated asthma (group 2). Clinical data were obtained and nasopharyngeal samples were collected through nasopharyngeal aspirate or swab and analysed via indirect fluorescent immunoassays to detect influenza A and B viruses, parainfluenza 1-3, adenovirus and respiratory syncytial virus. Rhinovirus was detected via molecular assays. Potential risk factors for asthma exacerbation were identified in univariate and multivariate analyses. Results: In 153 children (group 1: 92; group 2: 61), median age 7 and 8 years, respectively, the rate of virus detection was 87.7%. There was no difference between groups regarding the frequency of virus detection (p = 0.68); however, group 1 showed a lower frequency (19.2%) of inhaled corticosteroid use (91.4%, p <0.01) and evidence of inadequate disease control. In the multivariate analysis, the occurrence of three or more visits to the emergency room in the past 12 months (IRR = 1.40; p = 0.04) and nonadherence to inhaled corticosteroid (IRR = 4.87; p <0.01) were the only factors associated with exacerbation. Conclusion: Our results suggest an association between asthma exacerbations, poor disease control and nonadherence to asthma medication, suggesting that viruses may not be the only culprits for asthma exacerbations in this population

Monitoring the circulation of rotavirus among children after the introduction of the RotarixTM vaccine in Goiânia, Brazil

The epidemiological features of rotavirus A (RVA) infection differ between children from developing and developed countries which could result in differences in vaccine efficacy around the world. To evaluate the impact of RotarixTM on RVA prevalence, we monitored RVA genotypes circulating in Goiânia by monitoring virus in faecal samples from children that had or had not been previously vaccinated. From February-November of 2008, 220 faecal samples were collected from children in seven day-care centres. RVA detection was performed by two methodologies and the results were confirmed by polyacrylamide gel electrophoresis. From the 220 samples, eight were RVA-positive (3.6%) and five were from children that had received either one or two doses of the vaccine. All positive samples were collected from children with diarrhoea during August and September. Genotyping of the RVA characterised five of the viral samples as genotype G2P[4] and one as G8P[4], suggesting that G2P[4] was the predominant circulating genotype in Goiânia during the study. The fact that vaccinated children were also infected by RVA suggests that the vaccine does not fully protect against infection by the G2[P4] RVA genotype