Serological evidence of hepatitis E virus infection (HEV) has been observed in both humans

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BackgroundHepatitis 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.MethodsSerum 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.ResultsThe 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.ConclusionsBoth 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.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2334-14-458) contains supplementary material, which is available to authorized users.

The age-specific prevalence of antibodies to hepatitis A virus (anti-HAV) was determined in two different population groups with low socio-economic status from Rio de Janeiro city, Brazil, whose serum samples were collected 17 years apart (Population 1, 1978; Population 2, 1995). In Population 2, analysis of the anti-HAV prevalence was also carried out with respect to environmental factors. Population 1 was composed of 520 stored sera collected from the umbilical cord of term neonates and children aged 1 month to 6 years. In population 2, 720 serum samples were collected from children and adolescents with ages ranging from 1 to 23 years. The overall prevalence rate of anti-HAV in Population 1 and Population 2 was 65.6% and 32.1%, respectively. In Population 1, the anti-HAV prevalence reached 88% at the age of 3, while in Population 2, it increased from 4.5% in children under the age of 3 to 66% in the group of adolescents over the age of 14. The low exposure to HAV infection in younger children from Population 2 could be a result of improved environmental hygiene and sanitation, as demonstrated by the presence of piped water, waste and sewage disposal systems in most houses from this population group. These findings indicate a possible change in the prevalence of hepatitis A in Rio de Janeiro.

The prevalence of hepatitis A virus (HAV)

We investigated the seroprevalence of hepatitis A virus (HAV) and hepatitis E virus (HEV) infection in subjects living in the community of Manguinhos, Rio de Janeiro, Brazil, and assisted Key words: hepatitis A virus -hepatitis E virus -seroprevalence -epidemiology -Rio de Janeiro -Brazil Viral hepatitis is a public health problem worldwide. Two of the agents that cause viral hepatitis are enterically transmitted: hepatitis A virus (HAV) and hepatitis E virus (HEV).In the last years, improvements in environmental sanitation and hygienic conditions, such as piped water and sewage system, have been responsible for a decrease in the endemicity level of hepatitis A in several developing countries. In Brazil, although hepatitis A is considered an endemic disease (Pannuti et al. 1985, Abuzwaida et al. 1987, Bensabath et al. 1987, Queiroz et al. 1995, data published in recent investigations carried out in the State of Rio de Janeiro revealed a shift in the hepatitis A epidemiological pattern. Improvements in life standards of some urban populations are responsible for a decrease in antibody prevalence among children and adolescents (Vitral et al. 1998a,b).HEV infection is quite common in some geographic areas like India, Africa and Southeast Asia, where it can represent the main cause of acute hepatitis (Arankalle et al. 1995 reported in these areas (Shakhgildyan et al. 1986, CDC 1987, Belyakov et al. 1990, Zuang 1992. On the other hand, epidemiological investigations in non-endemic areas show a low, but constant presence of anti-HEV antibodies (about 1.2%) in normal human populations (Balayan et al. 1996, Psichogiou et al. 1996, Irshad 1999.In 1986, the occurrence of outbreaks of HEV infection in the Americas was recognized in Mexico (Velazquez et al. 1990). More recently, two acute cases of hepatitis E were described in Argentina (Schlauder et al. 2000). In Brazil, outbreaks of hepatitis E have never been reported, although some authors found antibodies in some population groups (Focaccia et al. 1995, Parana et al. 1997, Souto & Fontes 1998, Trinta et al. 2001.Nowadays, hepatitis A can be prevented by active immunoprophylaxis and, for a better control of infection, it is necessary to investigate its current prevalence in different areas. On the other hand, further data are needed in order to evaluate the importance of HEV infection in our country. The aim of the present study was to evaluate the prevalence of HAV and HEV infections in an area where sanitary conditions were improved over the last few years. MATERIALS AND METHODSCalculation of sample size -The minimum sample size was estimated using the formula: n = Z² P Q / d², considering as n = estimated sample size; Z = reduced variable, which value is 1,96 when alpha = 0,05; P (estimated prevalence) = probability to achieve the studied phenomenon; Q (1-P) = complement of the estimated prevalence; d (desired precision) = margin of error.

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