Early diagnosis of acute hepatitis B infection is done by:March 2011
Correct Answer: Presence of IgM anti-HBc in serum
Description: Ans. B: Presence of IgM anti-HBc in serumAlthough HBsAg is the earliest virological marker in serum of patients with acute hepatitis B, it does not help in establishing the diagnosis of acute Hepatitis B infection (it may be seen in chronic cases or carrier state)It is the presence of IgM anti-HBc that confirms an acute Hepatitis B infectionHBsAgThe hepatitis B surface antigen (HBsAg) is most frequently used to screen for the presence of this infection. It is the first detectable viral antigen to appear during infection.However, early in an infection, this antigen may not be present and it may be undetectable later in the infection as it is being cleared by the host.Anti-HBc IgMThe infectious virion contains an inner "core paicle" enclosing viral genome. The icosahedral core paicle is made of 180 or 240 copies of core protein, alternatively known as hepatitis B core antigen, or HBcAg.During this 'window' in which the host remains infected but is successfully clearing the virus, IgM antibodies to the hepatitis B core antigen (anti-HBc IgM) may be the only serological evidence of disease.HbeAg and anti-HBeSholy after the appearance of the HBsAg, the hepatitis B e antigen (HBeAg) will appear.Traditionally, the presence of HBeAg in a host's serum is associated with much higher rates of viral replication and enhanced infectivityDuring the natural course of an infection, the HBeAg may be cleared, and antibodies to the 'e' antigen (anti-HBe) will arise immediately afterwards.This conversion is usually associated with a dramatic decline in viral replication.Anti-HBs and anti-HBc IgGIf the host is able to clear the infection, eventually the HBsAg will become undetectable and will be followed by IgG antibodies to the hepatitis B surface antigen and core antigen, (anti-HBs and anti HBc IgG).The time between the removal of the HBsAg and the appearance of anti-HBs is called the window period.A person negative for HBsAg but positive for anti-HBs has either cleared an infection or has been vaccinated previously.Hepatitis B carriersIndividuals who remain HBsAg positive for at least six months are considered to be hepatitis B carriers.Carriers of the virus may have chronic hepatitis B, which would be reflected by elevated serum alanine aminotransferase (ALT) levels and inflammation of the liver, as revealed by biopsy.Carriers who have seroconveed to HBeAg negative status, paicularly those who acquired the infection as adults, have very little viral multiplication and hence may be at little risk of long-term complications or of transmitting infection to others.PCR testsThey have been developed to detect and measure the amount of HBV DNA, called the viral load, in clinical specimens.These tests are used to assess a person's infection status and to monitor treatment.Individuals with high viral loads, characteristically have ground glass hepatocytes on biopsy.
Category:
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