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The presence of
hepatitis B surface antigen (HBsAg) is regarded as the most
important marker of infectivity, irrespective of viral load.
Commonly used terms for hepatitis B are mentioned in table 1.3
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Table 1. Glossary of clinical terms used in HBV infection
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DEFINITIONS
Chronic
hepatitis B
Chronic necroinflammatory disease of the liver caused by
persistent infection with hepatitis B virus.
Chronic hepatitis B can be subdivided into-
· HBeAg positive chronic hepatitis B and
· HBeAg negative chronic hepatitis B
Inactive HBsAg
carrier state
Persistent HBV infection of the liver without significant,
ongoing necroinflammatory disease.
Resolved
hepatitis B
Previous HBV infection without further virological, biochemical
or histological evidence of active virus infection or disease.
Acute
exacerbation or flare of hepatitis B
Intermittent elevations of aminotransferase activity to more
than 10 times the upper limit of normal and more than twice the
baseline value.
Reactivation
of hepatitis B
Reappearance of active necroinflammatory disease of the liver in
a person known to have the inactive HBsAg carrier state or
resolved hepatitis B.
HBeAg
clearance
Loss of HBeAg in a person who was previously HBeAg positive.
HBeAg
seroconversion
Loss of HBeAg and detection of anti-HBe in a person who was
previously HBeAg positive and anti-HBe negative.
HBeAg
reversion
Reappearance of HBeAg in a person who was previously HBeAg
negative, anti-HBe positive.
DIAGNOSTIC CRITERIA
Chronic
hepatitis B
1. HBsAg + > 6 months
2. Serum HBV DNA >105 copies/ml
3. Persistent or intermittent elevation in ALT/AST levels
4. Liver biopsy showing chronic hepatitis (necroinflammatory
score >_4)*
Inactive HBsAg
carrier state
1. HBsAg+ > 6 months
2. HBeAg-, anti-HBe+
3. Serum HBV DNA <105 copies/ml
4. Persistently normal ALT/AST levels
5. Liver biopsy confirms absence of significant hepatitis
(necroinflammatory score <4)*
Resolved
hepatitis B
1. Previous known history of acute or chronic hepatitis B or the
presence of anti-HBc ± anti-HBs
2. HBsAg-
3. Undetectable serum HBV DNA#
4. Normal ALT levels
* Optional
# Very low levels may be detectable using sensitive PCR assays |
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Based on the inter
group divergence of 8% or more in the complete genome nucleotide
sequence, HBV has been classified into at least eight genotypes
(A-H). Each genotype has its distinct geographical and ethnic
distribution shown in table 2.4
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Table 2. Genotypes of HBV |
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Genotype |
Geographic distribution |
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1.A |
Northern Europe, Africa, United
states |
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2.B and C |
Asia |
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3.D |
Southern Europe, Middle East |
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4.E |
Africa |
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5.F and H |
Central and South America |
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6.G |
Africa |
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7.A, B, C and D |
United States |
Genotypes A and D occurs frequently in
Africa, Europe and India, while genotypes B and C are prevalent in
Asia. A study from India indicated that genotype D is more often
associated with HBeAg negative chronic hepatitis B, more severe
diseases and may predict the occurrence of HCC in young patients.5
DISEASE BURDEN IN BANGLADESH
Hepatitis B is a major cause of chronic liver disease and a
significant public health issue. Between 350 million to 400 million
people worldwide are chronically infected with HBV.3 The HBV
prevalence in Bangladesh is 2.3 to 9.7 percent with an approximate
carrier pool of 10 million.6
These include healthy adult population 4.4 to 9.7%, healthy children
3%, schoolgirls 2.3%, a rural community 6.4%, and slum communities
3.8%. Perinatal or vertical transmission of HBV in Bangladesh is
infrequent due to a low HBeAg positivity rate (30.1%) among pregnant
females with HBV infection.
Among the high-risk population HBV carrier rate that varies widely
such as professional blood donors 19.0 to 29.0%, family members of
HBsAg carrier 20.6%, health care workers 8.7%, parenteral drug
abusers 6.2 to 12.0%, truck drivers 5.9%, commercial sex workers
9.7%, multiple units of blood recipients 13.8%. HBV is an important
cause of liver disease in Bangladesh and is responsible for 19.0 to
35.0% of acute viral hepatitis, 35.7% of acute liver failure, 33.3
to 40.5% of chronic hepatitis and 46.8% of hepatocellular carcinoma.
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