In Rondônia State, Brazil, two IntroduçãoAs transformações ambientais realizadas pelo homem visando o desenvolvimento e o crescimento da economia são necessárias dentro do contexto social e devem ser realizadas seguindo-se padrões legais, visando causar os menores impactos possíveis. Ambientes aquáticos são amplamente utilizados pelo homem com as mais diferentes finalidades, entre elas o abastecimento de água, geração de energia, irrigação, navegação, piscicultura ou mesmo paisagismo 1 .A construção de barragens para implantação de Usinas Hidrelétricas (UHE) é uma necessidade para o desenvolvimento de uma micro e/ou macro região, pois a oferta de energia elétrica atrai novos investimentos e, com isso, haverá o crescimento da economia local. A Região Norte do Brasil é rica em recursos hídricos. Segundo a Agência Nacional de Energia Elétrica (ANEEL; http://www.aneel.gov.br, acessado em 07/Set/2005), o potencial hidráulico, ou hidroenergético, do país é de 260GW, dos quais apenas 25% estão sendo utilizados para a produção de energia pelas UHE de médio e grande porte e pelas Pequenas Centrais Hidrelétricas (PCH). A Região Norte tem o maior potencial para geração hidráulica com 114GW, ou 44%.Para o Estado de Rondônia, estão planejadas a construção de seis UHE (Jirau, Santo Antônio, Madeira Binacional, Monte Cristo, Ávila e Ji-Paraná) e duas PCH (Cachimbo e Alta Floresta), que

High seroprevalence of hepatitis B and C markers in the upper Madeira River region, Porto Velho, Rondônia State, Brazil Alta soroprevalência dos marcadores das hepatites B e C na região do alto rio Madeira, Porto Velho, Rondônia, Brasil Alta seroprevalencia de los marcadores de las hepatitis B y C en la región del alto río Madeira, Porto Velho, Rondônia, Brasil 25% of patients .Antibodies against the hepatitis C virus (HCV) are found in 2.5% to 4.9% of the Brazilian population; that is, approximately 3.9 to 7.6 million people are infected by this 4 virus . The risk of developing liver cirrhosis and/or cancer is 4,18 high in this group .The state of Rondônia in West Amazonia is an area with a high endemicity of hepatitis B and C, possibly due to past doi: 10.5123/S2176-62232010000200011 ABSTRACT A seroprevalence study on the serologic markers of hepatitis types B and C on the inhabitants of the upper Madeira River, between the communities of Santo Antonio and Abunã, in the Municipality of Porto Velho, Rondônia State, was conducted. This locality will be flooded by two new hydropower plants yet to be built in the Madeira River. Local population was estimated in 5 thousand individuals, according to Instituto Brasileiro de Geografia e Estatística's (Brazilian Institute of Geography and Statistics) census. A sample of 10% of the population was randomly selected. Five milliliters of peripheral venous blood were collected in Vacutainer® dry tubes, and the serum samples were maintained in a freezer at -20º C. ELISA serological tests (DiaSorin, Inc.) were performed according to the manufacturer's methodology for the following viral markers: total Anti-HBc, HBsAg, Anti-HBs and Anti-HCV. After the processing of 431 samples, the results were: 192 (44.5%) were positive for total Anti-HBc, 29 (6.7%) were positive for HBsAg, 230 (53.4%) were positive for Anti-HBs, and 32 (7.4%) were positive for Anti-HCV. We concluded that this region presented an intermediate and a high prevalence rate for hepatitis B and C, respectively, according to the World Health Organization. The high prevalence (more than 50%) of individuals immune to hepatitis B leads us to the conclusion that in the next decades problems related to that type of hepatitis tend to decrease, whereas the incidence of hepatitis C will probably increase. Migration of thousands of new inhabitants drawn by the implementation of the new hydropower plants in this region has the potential of worsening the public health issues related to these viral hepatitis infections.Keywords: Hepatitis B; Hepatitis C; Serology; Enzyme-Linked Immunosorbent Assay; Cross-Sectional Studies. lapses in prenatal care and the low quality of blood transfusions in addition to other social or cultural factors, such as sexual promiscuity or sharing of personal hygiene 11 products .Previous studies performed in rural areas of Rondônia found a prevalence of 67.9% for anti-HBc total antibodies and 7.8% for HBsAg (Villalobos-Salcedo, personal communication).In accordance with the local data on their high pr...