The Amazon region of Brazil is an area of great interest
because of the large distribution of hepatitis B virus in
specific Western areas. Seven urban communities and 24 Indian
groups were visited in a total of 4,244 persons. Each
individual was interviewed in order to obtain demographic and
familial information. Whole blood was collected for serology
and genetic determinations. Eleven genetic markers and three
HBV markers were tested. Among the most relevant results it
was possible to show that (i) there was a large variation of
previous exposure to HBV in both urban and non-urban groups
ranging from 0 to 59.2%; (ii) there was a different pattern of
epidemiological distribution of HBV that was present even
among a same linguistic Indian group, with mixed patterns of
correlation between HBsAg and anti-HBs and (iii) the
prevalence of HBV markers (HBsAg and anti-HBs) were
significantly higher (P=0.0001) among the Indian population
(18.8%) than the urban groups (12.5%). It is possible that the
host genetic background could influence and modulate the
replication of the virus in order to generate HB carrier
state.
