Variação sazonal da infecção pelo vírus da hepatite A no Rio de Janeiro, Brasil

Hepatitis A virus (HAV) infection constitutes a major public health problem in Brazil. The transmission of HAV is primarily by fecal-oral route so the water is an important vehicle of HAV dissemination. There is a great incidence of acute cases of hepatitis A in some areas of Brazil however the seasonal variation of these cases was not documented. The aim of this study was to determine the seasonality of HAV infection in Rio de Janeiro. From January 1999 to December 2001, 1731 blood samples were collected at the National Reference Center for Hepatitis Viruses in Brazil (NRCHV). These samples were tested by a commercial enzyme-immunoassay to detect anti-HAV IgM antibodies. Yearly positive rates were 33.74% in 1999, 32.19% in 2000, and 30.63% in 2001. A seasonal variation was recognized with the highest incidence in spring and summer. Furthermore a seasonal increase in incidence of HAV infection was found during the rainy season (December to March) because the index of rains is very high. It is concluded that HAV infections occur all year round with a peak during hot seasons with great number of rains.A infecção pelo vírus da hepatite A constitui um dos maiores problemas de saúde pública no Brasil. A transmissão do HAV ocorre principalmente pela via orofecal deste modo a água é um importante veículo da disseminação do HAV. Existe uma alta incidência de casos agudos de hepatite A em algumas áreas do Brasil entretanto a variação sazonal destes casos não foi relatada. O objetivo deste estudo foi avaliar a sazonalidade da infecção pelo HAV no Rio de Janeiro. De janeiro de 1999 a dezembro de 2001, 1731 amostras de sangue foram coletadas no Centro Nacional de Referência para Hepatites Virais no Brasil (CRNHV). Estas amostras foram testadas por um ensaio imunoenzimático comercial para detectar anticorpos IgM anti-HAV. Taxas de positividade anuais foram de 33,74% em 1999, 32,19% em 2000, e 30,63% em 2001. Uma variação sazonal foi observada com um alto índice na primavera e verão. Também foi observado um aumento sazonal na incidência da infecção pelo HAV durante a estação chuvosa (Dezembro a Março) pois o índice de chuvas é muito alto. Foi concluído que a infecção pelo HAV ocorre o ano todo com um pico durante estações quentes com grande número de chuvas

Hepatitis A and E seroprevalence and associated risk factors: a community-based cross-sectional survey in rural Amazonia

Abstract\ud \ud Background\ud Hepatitis A virus (HAV) and hepatitis E virus (HEV) are both transmitted by the faecal-oral route, and represent common causes of acute hepatitis in developing countries. The endemicity of HAV infection has shifted from high to moderate in Brazil. Human cases of HEV infection seem to be rare, although the virus has been detected in swine livestock and effluents of slaughterhouses. This study was to determine the epidemiology of hepatitis A and E in one of the largest agricultural settlements in the Amazon Basin of Brazil.\ud \ud \ud Methods\ud Serum samples collected from 397 individuals aged between 5 and 90 years during a population-based cross-sectional survey were tested for anti-HAV and anti-HEV antibodies. Associated risk factors and spatial clustering of HAV and HEV seropositivity were also analyzed.\ud \ud \ud Results\ud The overall rate of HAV seropositivity was 82.9% (95% confidence interval (CI), 79.2-86.6%). Multilevel logistic regression analysis identified increasing age (in years; odds ratio (OR), 1.097; 95% CI, 1.050-1.147; P < 0.001) and crowding (OR, 1.603; 95% CI, 1.054-2.440; P = 0.028) as significant risk factors for HAV seropositivity. Anti-HEV IgG was detected in 50/388 settlers (12.9%, 95% CI, 9.5-16.2%). Anti-HEV IgM was detected in 7/43 (16.3%) anti-IgG positive samples, and 4 of them had a confirmed result by immunoblot. Increasing age was the only significant determinant of HEV seropositivity (OR, 1.033; 95% CI, 1.016-1.050; P < 0.001). No significant spatial clustering of HAV and HEV seropositivity was detected in the area.\ud \ud \ud Conclusions\ud Both HAV and HEV are endemic, with differing rates of infection in children and adults in this rural setting of the Brazilian Amazon. Anti-HEV prevalence was considerably higher than those previously reported in Brazil. The detection of HEV- specific IgM antibodies in four asymptomatic individuals is highly suggestive of the circulation of HEV in this rural population.This work was supported by grants from the Fundação de Amparo à\ud Pesquisa do Estado do Rio de Janeiro (FAPERJ E-26/ 110.278/2012 - APQ1)\ud and Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP,\ud 05/51988-0). MdSN was supported by a PhD scholarship from FAPESP, RCCP\ud was supported by a CNPq scholarship. MUF, MAP, and AMCG receive sênior\ud research scholarships from the Conselho Nacional de Desenvolvimento\ud Científico e Tecnológico (CNPq), Brazil.\ud Vitral et al. BMC Infectious Diseases 2014, 14:458 Page 7 of 9\ud http://www.biomedcentral.com/1471-2334/14/458\ud We would like to thank the inhabitants of Ramal do Granada for their\ud enthusiastic participation in the study; Adamílson L. de Souza for their help in\ud fieldwork, and Estéfano A. de Souza and Bruna A. Luz for data management