skjeev
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08.19.06 (2 years ago)
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HEPATITIS B
The incubation period of Hepatitis B usually lasts from 2 to 4 months, although it may be very short (10 days) or extremly long (9 months). Yet before the outbreak of the acute disease HBs- and HBe-antigen are detectable in the patient's serum.
The onset of acute hepatitis is characterized by the occurrence of anti-HBc antibodies which at first exclusively belong to the IgM class. From this time on anti-HBc antibodies will be detectable in the patient's serum for the rest of his life, no matter whether there is an acute Hepatitis B, a form of persisting virus infektion or some naturally acquired immunity to HBV. The IgM anti-HBc antibodies are detectable not during acute hepatitis, but sometimes also for considerable lengths of time into the stage of immunity, and furthermore in many phases of chronic Hepatitis B virus infection, so that the qualitative identification of IgM anti-HBc is not sufficient for diagnosing acute Hepatitis B.
If this disease proceeds without any complications, seroconversion of HBe-antigens will occur within a period of 10 weeks, with anti-HBe antibodies appearing in the serum some time after or simultaneously with the disappearance of HBe-antigen.
Seroconversion of HBs-antigen to anti-HBs antibodies follows this event within a period of 6 months after the onset of the disease. In this process we usually find a "window-stage" of some weeks to some month's duration, in which HBsAg is no longer and anti-HBs antibodies are not yet detectable . In some cases the HBeAg and/or HBsAg seroconversions will proceed without any window-stage, so that one serum sample may contain both HBe-antigen and anti-HBe (or HBs-antigen and anti-HBs) simultaneously.
The anti-HBs and anti-HBe antibodies---together with the anti-HBc antibodies---can persist for the whole of a patient's life after resolution of the acute hepatitis and will be characteristic of the stage of immunity. In most cases, however, the anti-HBe antibodies are less long-lived, and the anti-HBs antibodies may also drop below the level where identification is possible after some years.
Injection of Hepatitis B hyperimmune globulin results in a transitory, active Hepatitis B vaccination in a lasting level of anti-HBs antibodies in the serum.
The most significant event indicating a chronic course of Hepatitis B is the absence of the HBsAg/anti-HBs seroconversion. If this phenomenon has not occured within 6 months after the onset of the disease, persistence of the Hepatitis B virus infection and the related clinical pictures (asymptomatic HBsAg carrier, chronic hepatitis, cirrhosis, or hepatoma) have to be reckoned with.
In the least favourable form of the disease HBe-antigen and IgM anti-HBc antibodies will be detectable in the patient's serum for several years. Although the HBeAg/anti-HBe seroconversion is a favourable prognostic sign, even anti-HBe-positive chronic hepatitis may take a severe course. If the HBe-antigen phase is relatively short, we will mostly be confronted with the picture of an asymptomatic carrier, in which at last---in the stage of inapparent virus persistance---even HBsAg will no longer be detactable . The dissappearance of HBe-antigen does not always signal a favourable course of the disease; after a short period of anti-HBe-positive results HBeAg may reoccur and the disease be reactivated.
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