Occult B infection in the Brazilian northeastern region: a preliminary report

Abstract

A sentinel study on viral hepatitis is currently being carried out in the village of Cavunge in a semiarid rural region of the state of Bahia, northeastern Brazil. This study has identified individuals in whom anti-HBc IgG was the only serological marker for hepatitis B virus (HBV). This serological pattern may constitute evidence of occult HBV infection. This study Investigated the possibility of occult hepatitis B virus infection in individuals in a rural community who tested positive for anti-HBc IgG alone. A cross-sectional population-based study. ELISA III was performed on serum samples to test for serological viral markers, and ultrasensitive PCR (US-PCR) was used to assess viremia. Among the 1,536 serum samples, 3.6% (n=55) were positive for anti-HBc alone. Four years after this first serological survey, 31 of those 55 individuals (56.3%) were retested, and 11 (35.5%) remained anti-HBc positive alone. Two of these 31 (6.5%) were HBV-DNA positive based on US-PCR, with normal aminotransferase levels in both cases. Cases of occult hepatitis B infection were identified in this semiarid rural community of northeastern Brazil, where endemicity of HBV is moderate. Key-Words: Anti-HBc alone, hepatitis B virus, occult hepatitis B, ultrasensitive PCR.Approximately 400 million people worldwide are chronic hepatitis B carriers. Despite vaccination, serological tests performed in hemotherapy services, and programs for the prevention of sexually transmitted infections, the number of hepatitis B virus (HBV)-infected individuals remains high, with prevalence ranging from 0.1% to 20% [1].The serological marker most widely used to detect exposure to HBV is HBcAg IgG; however, this marker is unable to define the status of the HBV carrier [2]. In individuals in whom antibody against the core protein (anti-HBc IgG) is the only positive marker, there are various possible explanations for false-positive test results, including patients with past, resolved infection, in whom the antibody against hepatitis B surface antigen (anti-HBs) is not present, occult HBV infection due to mutation of the S gene, or very low viral replication [3]. In this last hypothesis, analysis for HBV-DNA is considered the most sensitive diagnostic method [4].Clearance of hepatitis B surface antigen (HBsAg) generally indicates seroconversion to anti-HBs and consequent remission of HBV infection [5]. However, several researchers have shown that seroconversion to anti-HBs is not necessarily indicative of virological cure. In this case, an occult, silent or latent hepatitis B infection may be characterized by presence of viral DNA alone, while the patient tests negative for HBsAg or anti-HBc [6]. A clear example is the diagnosis of this infection in patients with chronic hepatitis of undefined etiology (cryptogenic hepatitis), comorbid hepatitis C virus (HCV), HIV carriers, patients with chronic renal failure or patients with hepatocellular carcinoma [7,8]. There are also case reports of hepatitis B transmission following blood transfusion or organ donation...

Molecular epidemiology of hepatitis B virus among the indigenous population of the Curuçá and Itaquaí Rivers, Javari Valley, State of Amazonas, Brazil

“…This goes against some studies that indicate greater prevalence among men 17,19 and other studies that show a higher caseload among women 22 . It is the view of the researchers, however, that men are probably more exposed to sources of infection due to behavioral aspects such as drug use, promiscuity, infrequent prophylactic use, greater frequency of travel outside of the indigenous areas, and decorative body piercings.…”

“…Barros-Junior et al 18 reported a lower prevalence in 51 (17.6%) patients of the Brazilian Amazon. In studies conducted in the States of Bahia and Mato Grosso do Sul the prevalence was 18% and 24.7% 19,20 , respectively, showing that HBV-DNA prevalence is quite heterogeneous in Brazil.…”

Occult Hepatitis B Virus (HBV) Infection: a Global Challenge for Medicine

“…For example, Minuk et al reported that HBV-DNA was detected in 14/487 (2.87%) Inuit people (Canada) [42]. Brazilian investigators showed that 2 of 1536 (0.13%) blood donors were infected with OBI [43]. Interestingly, Gutierrez et al from Venezuela revealed that no OBI cases were found in 2,075 screened blood samples [44].…”

Perfiles serológicos de hepatitis B en donantes de sangre con anti-HBc reactivos

“…La resolución del HBsAg indica generalmente seroconversión al anticuerpo contra el antígeno de superficie del VHB (anti-HBs) y la consecuente remisión de la infección por el VHB (14), es importante determinar el nivel de anti-HBs en IU/L, para establecer la infectividad, títulos mayores de 100 IU/L indican generalmente que el individuo no es infectante (15).…”

“…Así mismo, pueden presentarse individuos en los que el anti-HBc de tipo IgG (anti-HBcIgG) es el único marcador de memoria positivo: resultados falso-positivos, pacientes que tuvieron la infección y se resolvió, pacientes que no han generado títulos de anti-HBs, pacientes con infección con el VHB que no presentan reactividad en el HBsAg, debido a la mutación del gen S, o en casos de replicación viral muy baja (14).…”