Emerging Trends in Epidemiology of Hepatitis B Virus Infection

Abstract

Although a vaccine against hepatitis B virus (HBV) has been available since 1982, the prevalence of adults with chronic HBV infection in sub-Saharan Africa and East Asia is still estimated at 5-10%. A high rate of chronic infections is also found in the Amazon and the southern parts of eastern and central Europe. In the Middle East and the Indian subcontinent, the prevalence is 2-5%. Less than 1% of the population of Western Europe and North America is chronically infected. Given the high prevalence of infections (such as hepatitis) among inmates, prison is considered a reservoir for facilitating such infections. Based on these premises, this current review examines and discusses emerging trends in the epidemiology of HBV infection, with particular attention to HBV infection in prison. The hepatitis B surface antigen (HBsAg) prevalence in prisoners in west and central Africa is very high (23.5%). The Centers for Disease Control and Prevention has highlighted the importance of HBV blood screening and subsequent anti-HBV vaccination in the prison population. The vaccination was recommended for all inmates, representing an opportunity to prevent HBV infection in a high-risk population. In these subjects, an accelerated hepatitis B immunisation schedule may result in rapid seroconversion for early short-term protection. Therefore, it is necessary to seek collaboration among public health officials, clinicians and correctional authorities to implement a vaccination programme.

Keywords: Anti-HBV vaccine; Chronic hepatitis B virus infection; Epidemiology; Prison; Public health.

Fig. 1.. Proposed algorithm after screening for HBV infection in prisoners.

A subject with anti-HBs and IgM anti-HBc negativity, but HBsAg and anti-HBc positivity is chronically infected. A subject with anti-HBs negativity, and HBsAg and IgM anti-HBc positivity is acutely infected. A subject with HBsAg negativity, and anti-HBc and anti-HBs positivity is immune due to natural infection. A subject with only anti-HBs positivity is immune due to HB vaccination. A subject with all markers showing negativity is susceptible to infection. Anti-HBc positivity, in the presence of HBsAg and anti-HBs negativity, can be found in the following cases: 1) resolved infection; 2) false positivity of anti-HBc; 3) resolving acute infection; and 4) occult infection. It could be useful to evaluate other markers (HBeAg, anti-HBe) and determine the viremia (HBV-DNA) and anti-HCV.

Fig. 2.. Response to vaccination in anti-HBc positive subjects.

In cases of isolated anti-HBc, test for HBeAg, anti-HBe and HBV-DNA to exclude HBV infection; test for anti-HCV as well. IgM anti-HBc positivity (≤6 months) indicates acute HBV infection. In cases of isolated presence of anti-HBc (IgM anti-HBc -), vaccination with a single dose of HBV vaccine could be indicated. Anti-HBs ≥10 IU/mL is due to the anamnestic response and this titre indicates that subjects are immune. Anti-HBs <10 IU/mL could indicate susceptibility to infection; In subjects who develop a primary response to 3 doses of vaccination, an isolated anti-HBc positive is probably false-positive. No response to vaccination suggests occult HBV infection. ^* due to the frequency of HBV-DNA in liver biopsy samples from HCV patients.