Seroprevalence of hepatitis B and C in the Western Brazilian Amazon region (Rio Branco, Acre): a pilot study carried out during a hepatitis B vaccination program

Abstract

In 1999, on the occasion of the application of the first vaccine dose during the state vaccination campaign against hepatitis B virus (HBV), 390 individuals from the town of Rio Branco, Acre, aged two or more years were selected for the determination of the seroprevalence of HBV and HCV. HBV markers (HBsAg, anti-HBs, and anti-HBc IgG) were determined on this occasion and anti-HBs antibodies were also assessed 30 days after the third vaccine dose. At the time of vaccination, 39% of the individuals were still susceptible to HBV, while 61% presented serologic evidence of previous HBV contact or previous vaccination. The individuals with previous HBV contact were significantly older (p<0.001) than those without HBV markers. Of the 192 individuals who returned for reexamination, 30 days after the third dose, 158 (82.3%) had received three vaccine doses, and only 60 (31.2%) belonged to the group without HBV markers. In these individuals, the seroconversion rate after the third dose was 92% (55/60). In conclusion, we found considerable HBV in this population, indicating the need for pursuing the immunization programs. We also found high rates of vaccination coverage in the Western Brazilian Amazon region.

Epidemiology and Molecular Characterization of Hepatitis B Virus Infection in Isolated Villages in the Western Brazilian Amazon

“…25,26,[35][36][37][38] The presence of HBsAg, the most commonly used marker to determine present infection, is an important tool for evaluating the mechanisms of transmission dynamics, its principal actors, and for identifying the population at potential risk of chronic liver disease. HBsAg = hepatitis B surface antigen; N = number of subjects; N+ = number of positive subjects; F = female; M = male; 95% CI = 95% confidence interval; *AOR = adjusted odds ratio for the following variables: age, village, past family history of clinical Malaria, vaccination against HBV, and presence of HBeAg-reactive in the Family; P value = statistical significance.…”

Seroprevalence of HBV, HCV and HIV co-infection in selected individuals from state of São Paulo, Brazil

“…In Brazil, the prevalence in the general population varies greatly from very low rates of 0.1% in the semi-arid Northeast Region (Focacia et al 1998, Tavares-Neto et al 2005, Figueiró-Filho et al 2007) to higher rates in the Amazon Region of 4-6% (Tavares- Neto et al 2004, Silva et al 2006, Paraná et al 2007). The HCV seroprevalence encountered in this study was similar to those found in some populations considered to be at risk for HCV infection, including 15% and 11% prevalence in alcoholics and chronic renal patients undergoing hemodialysis, respectively (Galperim et al 2006, Freitas et al 2008.…”

“…The nationwide epidemiological situation for HBV, HCV and HIV infections is difficult to quantify due to local and regional characteristics as well as the high number of asymptomatic infections (Tavares-Neto et al 2004, Silva et al 2006. Furthermore, most Brazilian studies, particularly ones dealing with hepatitis, were carried out in selected populations (e.g., prisoners, individuals with renal failure undergoing hemodialysis, intravenous injection drug users and health care workers) (Paraná et al 2007, Fialho et al 2008, Oliveira et al 2009).…”

Hepatitis B genotype G and high frequency of lamivudine-resistance mutations among human immunodeficiencyvirus/hepatitis B virus co-infected patients in Brazil

“…The prevalence of the HBsAg was estimated at less than 1% in the Northeast and CentralWest regions (Pereira et al 2009) and around 1% in the municipality of São Paulo (Focaccia et al 1998). In the Brazilian Amazon region, a higher prevalence was estimated to be 3.3-20.6% in some specific populations, such as certain indigenous groups (Braga et al 2001, 2005, Tavares-Neto et al 2004.…”