A comparative epidemiological study of hepatitis B and hepatitis D virus infections in Yanomami and Piaroa Amerindians of Amazonas State, Venezuela

Abstract

Summaryobjectives To report the prevalences of hepatitis B (HBV) and hepatitis D (HDV) infections in remote and more accessible Yanomami and Piaroa Venezuelan Amazonian Amerindian populations; to estimate incidence per susceptible.methods Clinico-epidemiological evaluation was carried out in 9 Piaroa villages. Blood samples were tested for HBV core antibody (anti-HBc), surface antigen (HBsAg) and HDV antibody (anti-HDV).Results were analysed using logistic regression, and estimates made of HBV forces of infection (FOI). Prevalences and FOI were also estimated for 4 Yanomami villages.results Mean Piaroa anti-HBc and HBsAg prevalences were 27.4% and 5.1%, respectively (up to 53% and 19% in the remote Autana region). Mean Yanomami anti-HBc and HBsAg prevalences were, respectively, 58.0% (range 43-70%) and 14.3% (31% in the village with highest HBsAg). No significant difference was found between sexes, with age and maternal HBsAg the only risk factors for HBV identified in multivariate regression of Piaroa data. Only 4 Piaroa and 2 Yanomami individuals were anti-HDV positive.conclusion Piaroa HBV prevalences were generally higher in remote villages than in less remote ones, with prevalences in Yanomami villages even higher. Anti-HBc prevalence was 47% in one Yanomami village with a history of HBV vaccination but no HBsAg cases were identified, suggestive of previously cleared or possibly transient infection or vaccine escape. Despite a past history of HDV epidemic outbreaks and HBsAg levels in some villages appearing sufficient to facilitate HDV transmission, anti-HDV prevalence was low; it remains to be established why no recent outbreaks have been reported.

Unusual presentation of hepatitis B serological markers in an Amerindian community of Venezuela with a majority of occult cases

“…As described previously, this community showed a lower rate of acquisition of anti-HBc antibodies (1.4% in individuals less than 15 years old), compared to the Yanomami for example (38% in individuals less than 15 years old) [2]. The lower prevalence of HBV exposure and infection in this Amerindian community may be due to its geographic location, since being located near the main urban centre of the state, it is closer to health services.…”

“…Total anticore antibodies (anti-HBc) prevalence was 17% (26/150) in this group and 31% (25/80) in individuals over 15 years of age [2]. Only 2 sera (1.3%) were positive for HBsAg [2]. These 2 sera were negative for anti-HBc antibodies.…”

“…However, the prevalence of active HBV infection, defined as positivity for HBV surface antigen (HBsAg) is variable among different Amerindian communities, coexisting in the same geographic environment [2]. In a recent study in the Venezuelan Amazon, anti-HBc prevalence ranged from 17 to 70% [2]. …”

“…Indeed, OBI has been already described in Mexican Amerindians [7]. The aim of this study was to characterize HBV infection among a Piaroa community, an Amerindian group which exhibits significant evidence of exposure to HBV but relatively low presence of HBsAg [2], and to explore the presence of OBI in this population.…”

Hepatitis B vaccine effectiveness in the face of global HBV genotype diversity

“…To our knowledge, comparable population-level data on the impact of universal infant vaccination is not available for countries in this region, but several studies have demonstrated a reduction in HBV infection following vaccination with recombinant vaccines in Peru [45], Venezuela [46] and Brazil [47]. Moreover, a recent analysis of the a determinant of HBsAg in 21 Chilean patients chronically infected with HBV genotype F revealed that none of their isolates contained changes that would affect binding to vaccination-associated anti-HBs [48].…”