Viral
hepatitis is a term commonly used for several clinically similar yet etiologically and epidemiologically distinct
diseases
Hepatitis B virus (HBV) infection is a global public health problem. The World Health
Organization estimated that, in 2015, there were 257 million HBV carriers in the world and roughly 887,000 died that year
from HBV-related liver
disease.
Hepatitis B virus (HBV) infection is considered a serious public health problem
worldwide, especially in less developed countries. It is estimated that 70% of
new chronic HBV infections
occur in low-income countries.
Hepatitis B virus (HBV) infection results in substantial human morbidity and
mortality, predominantly through the consequences of chronic infection. Recent
estimates of the number of people chronically infected with HBV have ranged from 240 million to 350 million.
It is estimated that
approximately two billion people worldwide have evidence of past or present
infection with hepatitis B virus (HBV),
and 257 million individuals are chronic carriers (ie, positive for hepatitis B
surface antigen [HBsAg])
The overall prevalence
of HBsAg is
reported to be 3.5 percent; however, it varies depending upon the geographic
area.
As an example, the
prevalence of chronic HBV in
adults ranges from 0.4 to 1.6 percent in regions of America, 1.2 to 2.6 percent
in Europe, 1.5 to 4.0 percent in Southeast Asia, 2.6 to 4.3 percent in the
Eastern Mediterranean, 5.1 to 7.6 percent in the Western Pacific, and 4.6 to
8.5 percent in the African regions
The lower prevalence in
children less than five years old reflects the effectiveness of the global
vaccination program against viral hepatitis B; however, there is a need for
higher vaccination coverage, in particular birth-dose HBV vaccine, to completely eliminate HBV infection among children.
The wide range in the
prevalence of chronic HBV infection
in different parts of the world is largely related to differences in the age at
infection, which is inversely related to the risk of chronicity. The rate of progression from acute to chronic HBV infection is approximately 90 percent for prenatally acquired infection
HBV was estimated to have resulted in 786,000 deaths, the vast
majority being attributable to liver cancer (341,000 deaths) and cirrhosis
(312,000 deaths.
However, the burden of HBV infection is geographically disparate, dependent on the
differing modes of transmission predominant in the population and the resulting
age at infection, which determines the probability of progression to infection.
In addition, the epidemiology of HBV infection
globally is changing because of the impact of universal infant vaccination
programs and through migration between high- and low-prevalence populations.
In countries where
chronic HBV infection
affects more than 8% of the population, the majority of these individuals were
infected at birth or in early childhood, when the risk of progression to chronicity is high. High-HBV prevalence
is common in much of the Asia Pacific and
sub-Saharan African regions of the world. Globally, it has been estimated that
45% of the world's population lives in an area of high prevalence. There is
evidence to suggest that vertical transmission is more common in Asia than in
Africa, where a greater proportion of women are highly infectious at
childbearing age, relating in part to predominant HBV genotypes that influence the likelihood of HBeAg positivity and high levels of HBV DNA during peak childbearing ages.
