Hepatitis B: changes in epidemiological features of Afro-descendant communities in Central Brazil

Abstract

Hepatitis B virus (HBV) infection is still a concern in vulnerable populations. in a study performed by our team in 1999-2003 in two Afro-Brazilian communities, Furnas dos Dionísios (FD) and São Benedito (SB), high prevalence rates of HBV exposure (42.7% and 16.0%, respectively), high susceptibility to HBV (55.3% and 63.0%) and low HBV vaccination like profile rates (2.0% and 21.0%) were observed. In 2015-2016, we reassessed HBV epidemiological and molecular features in these two communities to verify the impact of health actions adopted in the last years. the prevalence rate of HBV exposure among the enrolled 331 subjects was 35.3% in FD and 21.8% in SB. HBV chronic infection (5.8% in FD, 4.9% in SB) remained high. The rate of HBV vaccination like profile increased from 10.7% to 43.5% (2.0% to 45.9% in FD, 21.0% to 39.5% in SB) while susceptible subjects declined from 58.9% to 26.3% (55.3% to 18.8% in FD, 63.0% to 38.7% in SB). Among 18 HBsAg positive samples, 13 were successfully sequenced (pre-S/S region). Phylogenetic analyses showed that all isolates belong to HBV subgenotype A1, clustering within the Asian-American clade. Despite the maintenance of high prevalence rate of HBV exposure over these 13 years of surveillance, significant improvements were observed, reinforcing the importance of facilitated HBV vaccination to difficult-to-access population to close gaps in prevention. Hepatitis B virus (HBV) infection is still a major public health issue worldwide despite the availability of an effective vaccine and potent antiviral treatments 1-3. An estimated 2 billion people have been infected with HBV and 257 million people are chronic carriers of the virus. Serious complications of chronic HBV infection such as cirrhosis, liver failure, and hepatocellular carcinoma accounted for 887 000 deaths in 2015 4,5. Hepatitis B surface antigen (HBsAg) is the main HBV clinical marker indicating acute or chronic infection and its prevalence is used to categorize HBV endemicity as low, intermediate low, intermediate high, or high 2,6. Even though Brazil is now a low endemic country, it has some areas with high HBV prevalence, especially in the Amazon basin, some counties of Southern Brazil and, isolated communities 7-9. In Brazil, HBV immunization was first implemented in 1989 for infants in the western area of the Amazonas State and since 1998 HBV vaccine has been incorporated into the immunization schedule for infants as a national policy 10. Nowadays, HBV vaccination is available to all individuals regardless of age or risk group, being considered satisfactory and effective, moving Brazil from moderate HBV endemicity to low-endemicity classification 7. Although Brazilian multi-center population-based studies have observed a decrease in HBV infection prevalence in the last decades, especially among children and young adults 10,11 , vaccination is still a challenge in difficult-to-access populations and therefore, observations cannot be extrapolated to rural or vulnerable populations 7 .

Hepatitis B Virus Infection among Japanese Immigrants and Descendants: The Need to Strengthen Preventive and Control Measures

“…The association between HBV exposure and older age (>60 years old) found in this study has been reported previously [ 20 , 35 , 36 ]. It is noteworthy that most of the Japanese immigrants infected were over 60 years old, given Japanese immigration to Brazil has largely ceased since the mid-20th century.…”

“…A high susceptibility rate to HBV infection (67.3%) and a low positivity index for the serological marker of vaccine immunity (19.2%) were found in this group population, probably because it is predominantly older and has not received the HBV vaccine, highlighting that vaccination strategies and educational measures to control this infection should be considered in this population group. Similar to findings reported in other studies, increasing age was associated with HBV exposure, suggesting that people who were born before the initiation of vaccination programs were more likely exposed to the risk of infection [ 20 , 36 ].…”

“…In this study, a high prevalence rate of HBV exposure (13.5%: 95% CI: 12.1–14.9%) was found, which was high when compared to the prevalence found in blood prime donors (3.0%) from the same region [ 19 ]; this information reinforces the idea that Brazil has a heterogeneous distribution of HBV exposure despite the country’s low endemicity [ 5 , 20 ]. This rate is as high as another survey performed in Okinawa in the 1980s in which the prevalence of exposure varied from 3.0% in people aged 0–9 years old to 91.2% in people aged 30–39 years old [ 21 ].…”

Prevalence, Risk Factors and Vaccine Response against Hepatitis B in People Aged 50 Years or Older

“…However, the vaccine was made available free of charge to the entire population, regardless of age, only in 2015 [ 12 ]. Therefore, vaccination coverage in older adults is still incipient [ 13 , 14 ] and, associated with unsatisfactory vaccine performance in more advanced age groups, represents a challenge for public health.…”