Viral hepatitis

Posted by e-Medical PPT Wednesday, October 17, 2012
Viral hepatitis is a group systemic infection affecting the liver predominantly caused by 5 kinds of viruses at least
Viral hepatitis may be divided into 5 types according to etiology, that is hepatitis A, B, C, D and E
Although the agents can be distinguished by its antigenic properties, the 5 kinds of viruses may produce clinical similar illness
Clinical manifestations are characterized by anorexia, nausea, lassitude, enlarged liver and abnormal liver function, a part of cases may appear jaundice. Subclinical infection is common
Hepatitis A and E shows acute hepatitis, hepatitis B, C and D predispose to a chronic hepatitis and is related to liver cirrhosis and hepatic cancer
The course of acute hepatitis is about 2-4 months generally.
Recently, 2 kinds of viruses named HGV and TTV are discovered and considered to relate to viral hepatitis

Etiology
Hepatitis A virus (HAV)
HAV is one kind of picornavirus and used to be classified as enterovirus type72, but recently, it is considered to be classified as heparnavirus
Hepatitis A virion is a naked spherical particle, diameter 27nm
Consists of a genome of linear, single-stranded RNA, 7.5kb. The genome may be divided into 3 coding region: P1 region (encoding structural protein), P2 and P3 regions (encoding non-structure protein)
During acute stage of infection, HAV can be found in blood and feces of infected human and primates
Marmoset and chimpanzee are susceptible animals

Hepatitis B virus (HBV)
HBV is a kind of hepadnavirus
Three particles in serum:
       spherical particles and tubular particles with a  diameter of 20 nm, composed of HBsAg
        large particles with a diameter of 42 nm, named Dane particle. It consists of an outer protein shell (envelope, contain HBsAg) and an inner body ( core, contain HBcAg, HBeAg, HBV-DNA and DNAP )

Hepatitis  C virus (HCV)
HCV is a member of flavivirus family.
HCV genome is a single stranded positive-sense RNA and contains 9.4kb
The genome contains 5’-non coding region, C region, E region and NS region
HCV genome may be divided into many types and subtypes.
Resistance
Antigen-antibody system
The concentration of HCV in blood is low, HCV Ag has not be detected, anti-HCV is the indicator of infection and the marker of infectivity
HCV-RNA
     HCV-RNA may be detected from blood or liver tissue, it’s the direct evidence of infectivity

Pathology
Degeneration
Necrosis
Regeneration
Infiltration of inflammatory cells
Hyperplasia of interstitial cells

Acute viral hepatitis
The  degeneration of liver cells include
   ballooning degeneration,
   fatty degeneration,
   acidophilic degeneration
Cell nucleus vacuolar degeneration
Focal or spotty necrosis and regeneration
The infiltration of mononuclear cell, plasmocyte ,lymphocyte in portal area
Cholestasis and form of bile thrombas in bile capillaries of liver
Piecemeal necrosis

Chronic viral hepatitis
Mild chronic hepatitis G 1-2,S 0-2
Degeneration, spotty, focal necrosis, acidophilic body
Portal may have or no the infiltration of inflammation cell, mild PN or enlarged
The structure is intact
Moderate chronic hepatitis(CAH)
Portal area have obvious inflammation, with moderate PN
Severe inflammation with BN of intralobule
Form fibrous septum, most the structure of lobule reserved 
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