Frequency of pregnant women with HBsAg in a Brazilian community / Freqüência de gestantes portadoras do HBsAg em uma comunidade brasileira

ABSTRACT

The work reported here points up the real benefits provided by neonatal immunoprophylaxis of newborns delivered by mothers who are seropositive for the hepatitis B virus surface antigen HBs Ag and underscores the need to properly identify such mothers in Brazil so that immunoprophylaxis can be undertaken. To help determine levels of hepatitis B virus (HBV) infection and seropositivity for various HBV markers among pregnant women in Southeast Brazil, investigators studied 7992 pregnant women delivering at the Clinical Hospital of the University of São Paulo's Ribeirão Preto School of Medicine in Ribeirão Preto, Brazil. Seroreactivity for HBs Ag was determined first by serologic screening with an enzyme-linked immunosorbent assay (ELISA) procedure in which the sera were incubated for 2 hours and then by confirmation with another ELISA in which the sera were incubated for 18 hours. Subsequently, tests for anti-HBs Ag, HBe Ag, anti-HBe Ag, and anti-HBc Ag markers were conducted using confirmed positive samples. Initial screening found 84 of the 7992 samples (1.05%, 95% CI: 0.84-1.30) to be positive for HBs Ag; however, this HBs Ag positivity was confirmed in only 76 (0.95%, 95% CI: 0.75-1.19). The positivity rate was significantly higher among subjects whose pregnancies terminated in miscarriage (1.84%) than among those with live births (0.83%) (2, Yates correction = 7.6; P = 0.005). Anamnesis was able to identify HBV risk factors in only 27.6% of the confirmed HBs Ag-positive subjects or close household contacts. However, 21.3% (95% CI: 1.04-30.56) of the confirmed HBs Ag-positive subjects were found positive for HBe Ag, indicating a high risk of vertical transmission of the virus. These results demonstrate a need to conduct specific serologic research at term, in order to provide effective neonatal immunoprophylactic benefits

RESUMO

Visando aferir a tasa de reatividade sérica do HBs Ag e de outros marcadores da infecção pelo VHB em parturientes, além de avaliar quais os fatores de risco, estudaram-se 7992 mulheres que tiveram suas gestações resolvidas no Hospital das Clínicas da Universidade de São Paulo. A reatividade sérica do HBs Ag foi aferida por o teste ELISA em duas etapas: a primeira com período de incubação de 2 h (triagem) e a segunda de 18 horas (confirmatória) realizada nas amostras positivas ao triagem. Os marcadores anti-HBs Ag, HBeAg, anti-HBeAg, e anti-HBc Ag foram testados nas amostras confirmadamente positivas. No triagem, foram positivas para o HBs Ag 1,05% (IC95%; 0,84-1,30) das amostras. Apenas 0,95% (IC95%; 0,75-1,19) foram confirmadamente positivas, sendo significativamente superior nas pacientes cujas gestações terminaram em aborto (1,84%) do que as 0,84% que terminaram em parto (X2 correção de Yates = 7,76; P < 0,005). A anamnese possibilitou identificar fatores de risco para a infecção pelo VHB em apenas 27,6% das pacientes avaliadas. Dessas amostras, 21,3% (IC95%; 1,04-30,56) apresentavam HBeAg positivo, de elevado risco para transmissão vertical desse vírus. Esses resultados reforçam a necessidade de pesquisa sorológica específica no final da gestação, possibilitando o máximo benefícioda imunoprofilaxia neonatal