Page 625 - Textbook of Pathology, 6th Edition

isolated from stools, bile and liver of infected persons. 609
Serologic markers for HEV include the following:
1. Anti-HEV antibodies of both IgM and IgG class.
2. HEV-RNA.
However, testing for these markers for HEV is currently
not available.

Hepatitis G

A virus distinct from the foregoing hepatitis viruses has been
designated separately as hepatitis G (HGV). HGV infection
has been found in blood donors, patients on haemodialysis
and as coinfection with HIV. However, unlike HCV, HGV is
cleared from the plasma in majority of individuals while a
small percentage of cases have chronic HGV infection who
do not develop hepatitis, nor does infected blood require
Figure 21.11 Sequence of serologic and viral markers of HCV screening for HGV RNA.
infection.
HEPATITIS G VIRUS (HGV). HGV is a single-stranded
ii) Second generation antibodies are against C200 and C33c RNA virus. The virus has been identified by PCR ampli-
proteins and appear about one month earlier than the fication technique.
first generation.
iii) Third generation antibodies are against C22-3 and NS-5 CLINICOPATHOLOGIC SPECTRUM
region proteins and are detected even earlier. Among the various etiologic types of hepatitis, evidence
2. HCV-RNA. HCV infection is, however, confirmed by linking HBV and HCV infection with the spectrum of clinico-
HCV-RNA employing PCR technique which can be detected pathologic changes is stronger than with other hepatotropic CHAPTER 21
within a few days after exposure to HCV infection, much viruses. The typical pathologic changes of hepatitis by major
before appearance of anti-HCV and persists for the duration hepatotropic viruses are virtually similar. HAV and HEV,
of HCV infection. however, do not have a carrier stage nor cause chronic
hepatitis. The various clinical patterns and pathologic
PATHOGENESIS. Cell-mediated immune mechanism and consequences of different hepatotropic viruses can be
production of antiviral cytokines by T-lymphocytes certainly considered under the following headings:
play a role in hepatocytic injury due to HCV. HCV virions i) Carrier state
have not been identified in hepatocytes. Perhaps, HCV ii) Asymptomatic infection
infection of lymphoid cells may induce immunologic injury iii) Acute hepatitis
to hepatocytes. In patients with chronic HCV hepatitis, HCV- iv) Chronic hepatitis
specific CD4+ T cells and HLA-restricted CD8+ T cells have v) Fulminant hepatitis (Submassive to massive necrosis)
been identified. Crossreactivity between viral antigens and In addition, progression to cirrhosis (page 624) and
host autoantibodies to liver-kidney microsomal antigen (anti- association with hepatocellular carcinoma (page 634) are
LKM) have been reported in a subset of patients that explains known to occur in certain types of hepatitis which are
the association of autoimmune hepatitis and HCV hepatitis. discussed separately later. The Liver, Biliary Tract and Exocrine Pancreas

Hepatitis E I. Carrier State
Hepatitis E is an enterically-transmitted virus, previously An asymptomatic individual without manifest disease,
labelled as epidemic or enterically transmitted variant of non- harbouring infection with hepatotropic virus and capable of
A non-B hepatitis. The infection occurs in young or middle- transmitting it is called carrier state. There can be 2 types of
aged individuals, primarily seen in India, other Asian carriers:
countries, Africa and central America. 1. An ‘asymptomatic healthy carrier’ who does not suffer from
The infection is generally acquired by contamination of ill-effects of the virus infection but is capable of transmitting.
water supplies such as after monsoon flooding. However,
compared with HAV, secondary person-to-person infection 2. An ‘asymptomatic carrier with chronic disease’ capable of
does not occur with HEV. Thus HEV has some common transmitting the organisms.
epidemiologic features with HAV. HEV infection has a As stated before, hepatitis A and E do not produce the
particularly high mortality in pregnant women but is carrier state. Hepatitis B is responsible for the largest number
otherwise a self-limited disease and has not been associated of carriers in the world, while concomitant infection with
with chronic liver disease. HDV more often causes progressive disease rather than an
asymptomatic carrier state. There is geographic variation in
HEPATITIS E VIRUS (HEV). HEV is a single-stranded 32- incidence of HBV carrier state: while in normal population
34 nm, icosahedral non-enveloped virus. The virus has been in US and western Europe it is less than 0.5%, its prevalence