Epidemiologia molecular do vírus da hepatite B em população indígena dos rios Curuçá e Itaquaí no Vale do Javari, Estado do Amazonas

Abstract

Hepatitis B virus (HBV) infection is one of the most serious public health problems in the world. At least two billion people are infected, with over 350 million showing serological markers of active infection, despite prevention by vaccination. In Brazil, the HBV endemicity is heterogeneous, with the most prevalent disease in the north region. Among the indigenous population, epidemiological serum studies have reported high rates of hepatitis B prevalence in the Brazilian component of the Amazon rainforest. Studies have shown that in some cases the serological markers are not enough to detect viral activity, and in these situations, molecular tests are more sensitive and specific. The proposal of this study was to determine the prevalence of DNA (deoxyribonucleic acid) of hepatitis B virus in indigenous ethnic groups (Kanamary, Matis, Mayoruna, Marubo, Kulina and Korubo) in habitants of the rivers Curuçá and Itaquaí at the Javari Valley, Amazon, Brazil. This was a descriptive, cross-sectional study, such as used in case detection. One hundred and eighty (180) samples were analyzed from the indigenous communities of São Sebastião, Volta Grande, Pedro Lopes, Massapê, Remancinho and Bananeira. The samples were subjected to polymerase chain reaction (PCR) and semi-nested PCR to Hepatitis B virus, S gene. The prevalence for HBV-DNA of S gene was 51.1% (92/180). Among the PCR positive samples for HBV-DNA, 18/49 (36.7%) were from Marubo, 68/125 (54.4%) from Kanamary and 6/6 (100%) from other ethnicities. With regards to socio-demographic data, no significant difference was found (p=0.889) in relation to gender (statistical analysis at 5%). However, when analyzing age it was observed that the natives had lower median age (p<0.001) of 23 years old, suggesting that sexual activity was the main form of HBV transmission. There was no statistical difference found in relation to sources of infection and the presence of HBV DNA, as well as clinical aspects, with the exception of fever (p<0.001). The high prevalence of HBV-DNA of 75% (15/20) in pregnant women (p=0,009) demonstrates association with vertical transmission. The results confirm the high prevalence of HBV DNA in the Javari Valley, making it important to devise strategies for control and a more effective prevention in combating the spread of HBV