Epidemiological pattern and mortality rates for hepatitis A in Brazil, 1980-2002--a review.

The prevalence of hepatitis A virus (HAV) infection is high in developing countries, in which low standards of sanitation promote the transmission of the virus. In Latin America, which is considered an area of high HAV endemicity, most HAV-positive individuals are infected in early childhood However recent studies have shown that prevalence rates are decreasing. Herein, we review the data on HAV prevalence and outbreaks available in scientific databases. We also use official government data in order to evaluate mortality rates in Brazil over the last two decades. Studies conducted in the northernmost regions of Brazil have indicated that, although improved hygiene has led to a reduction in childhood exposure to HAV, the greatest exposure still occurs early in life. In the Southeastern region, the persistence of circulating HAV has generated outbreaks among individuals of low socioeconomic status, despite adequate sanitation. Nationwide, hepatitis A mortality rates declined progressively from 1980 to 2002. During that period, mortality rates in the Northern region consistently exceeded the mean national rate and those for other regions. Excluding the North, the rates in all regions were comparable. Nevertheless, the trend toward decline observed in the South was paralleled by a similar trend in the North.

Epidemiological pattern and mortality rates for hepatitis A in Brazil, 1980-2002: a review

The prevalence of hepatitis A virus (HAV) infection is high in developing countries, in which low standards of sanitation promote the transmission of the virus. In Latin America, which is considered an area of high HAV endemicity, most HAV-positive individuals are infected in early childhood. However, recent studies have shown that prevalence rates are decreasing. Herein, we review the data on HAV prevalence and outbreaks available in scientific databases. We also use official government data in order to evaluate mortality rates in Brazil over the last two decades. Studies conducted in the northernmost regions of Brazil have indicated that, although improved hygiene has led to a reduction in childhood exposure to HAV, the greatest exposure still occurs early in life. In the Southeastern region, the persistence of circulating HAV has generated outbreaks among individuals of low socioeconomic status, despite adequate sanitation. Nationwide, hepatitis A mortality rates declined progressively from 1980 to 2002. During that period, mortality rates in the Northern region consistently exceeded the mean national rate and those for other regions. Excluding the North, the rates in all regions were comparable. Nevertheless, the trend toward decline observed in the South was paralleled by a similar trend in the North.

Serological evidence of hepatitis E virus infection in different animal species from the Southeast of Brazil.

Serological evidence of hepatitis E virus infection (HEV) has been observed in both humans and different animal species living in non-endemic areas, suggesting that animals could be important reservoir for virus transmission to man. Antibodies to HEV have been detected in some Brazilian population groups. Nevertheless, sporadic cases of acute HEV infection have never been reported. We collected 271 serum samples from several domestic animals and also from pig handlers from Southeast of Brazil in order to investigate the seroprevalence of HEV infection. Anti-HEV IgG was detected in cows (1.42%), dogs (6.97%), chickens (20%), swines (24.3%), and rodents (50%), as well as in pig handlers (6.3%). The recognition of swine HEV infections in pigs in many countries of the world led us to investigate a larger sample of pigs (n = 357) from the same Brazilian region with ages ranging from 1 to > 25 weeks. IgG anti-HEV was detected in 100% of 7-day old pigs. Following a gradual decline between weeks 2 and 8 (probably due to loss of maternal IgG), the prevalence then steady increased until it reached 97.3% of animals older than 25 weeks. Besides the detection of anti-HEV antibodies in different animal species, the results showed that swine HEV infection seems to be almost universal within this Brazilian pig population. This is the first report that shows evidences of HEV circulation in Brazilian animal species and pig handlers.

Serological evidence of hepatitis E virus infection in different animal species from the Southeast of Brazil

Serological evidence of hepatitis E virus infection (HEV) has been observed in both humans and different animal species living in non-endemic areas, suggesting that animals could be important reservoir for virus transmission to man. Antibodies to HEV have been detected in some Brazilian population groups. Nevertheless, sporadic cases of acute HEV infection have never been reported. We collected 271 serum samples from several domestic animals and also from pig handlers from Southeast of Brazil in order to investigate the seroprevalence of HEV infection. Anti-HEV IgG was detected in cows (1.42 percent), dogs (6.97 percent), chickens (20 percent), swines (24.3 percent), and rodents (50 percent), as well as in pig handlers (6.3 percent). The recognition of swine HEV infections in pigs in many countries of the world led us to investigate a larger sample of pigs (n = 357) from the same Brazilian region with ages ranging from 1 to > 25 weeks. IgG anti-HEV was detected in 100 percent of 7-day old pigs. Following a gradual decline between weeks 2 and 8 (probably due to loss of maternal IgG), the prevalence then steady increased until it reached 97.3 percent of animals older than 25 weeks. Besides the detection of anti-HEV antibodies in different animal species, the results showed that swine HEV infection seems to be almost universal within this Brazilian pig population. This is the first report that shows evidences of HEV circulation in Brazilian animal species and pig handlers.

Studies on transmission of hepatitis A virus to squirrel monkeys.

Non-human primates have been playing an essential role in the study of hepatitis A virus (HAV) biology, pathogenesis and for testing candidate HAV vaccines. This study was to determine the suitability of squirrel monkeys (Saimiri sciureus) as animal model for HAV infection. Animals were inoculated, either intragastrically or intravenously, with a Brazilian HAV isolate (HAF-203). Alanine aminotransferase (ALT) and anti-HAV antibodies (IgM and total) were monitored. Feces were daily collected for HAV antigen and HAV RNA detection. Samples of liver tissue were obtained by biopsy before inoculation at peak ALT levels and/or when anti-HAV antibodies developed, and at necropsy for morphological examination. Monkeys inoculated by the intravenous route rapidly developed significant elevations of serum ALT, anti-HAV antibodies, and liver histologic changes, while the only evidence of HAV infection in intragastrically inoculated animals was the seroconversion. Moreover, squirrel monkeys excreted very low levels of HAV detectable in only few fecal samples after amplification by RT-PCR, different from humans and other non-human primate species that eliminate large quantities of virus during the late incubation period. The unusual onset of hepatitis A in experimentally infected squirrel monkeys represent an important obstacle for its use as animal model for the study of this viral infection. However, they can represent a valuable tool for the obtention of hyperimmune sera for HAV, in the view of the very high titer of anti-HAV developed (105) 24 days after a single intravenous inoculation.

Age-specific prevalence of antibodies to hepatitis A in children and adolescents from Rio de Janeiro, Brazil, 1978 and 1995. Relationship of prevalence to environmental factors

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 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 2 was 65.6 per cent and 32.1 per cent, respectively. In Population 1, the anti-HAV prevalence reached 88 per cent at the age of 3, while in Population 2, it increased from 4.5 per cent in children under the age of 3 to 66 per cent 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.