Case 47

Published on 18/02/2015 by admin

Last modified 18/02/2015

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CASE 47

ED is a 33-year-old man with a history of “globe-trotting” since the age of 18 and who has recently returned from a 4-month trip to Indonesia. He had declined all vaccinations before travel, with the exception of those (e.g., for yellow fever) demanded by the immigration authorities of the countries he wished to visit. Three weeks after his return his family noticed he was quite “yellow” about the face, and he felt listless and nauseated. His family physician ordered a variety of blood tests. Results of these show a picture of acute hepatitis, negative serology for hepatitis C or hepatitis A(E), but positive results for hepatitis B. You ask the laboratory for more detailed information on the immunoglobulin isotypes of the anti–hepatitis B antibodies. Why?

QUESTIONS FOR GROUP DISCUSSION

1. Obviously we can be wise with hindsight here and agree that ED should have received the standard hepatitis B vaccine at some time before he became naturally exposed. The big question now is whether he is a carrier of hepatitis B (infected a long time ago) or whether this is a new infection. Explain why testing for particular anti–hepatitis B isotypes would help you to determine this.

2. Draw a schematic of hepatitis B virus and show the following antigens: surface antigen HBsAg, core antigen HBcAg, and HBeAg, from which the HBcAg is derived.

3. During the course of hepatitis B infection, antibodies are generated that are specific for the antigens listed in question 2. Detection of antibodies to these various antigens plays an important role in determining the stage of infection. Explain why anti-HBs antibodies will not be detected until after the disappearance of HBsAg in serum, even though it is believed that these antibodies are produced early in the infection.

4. Study Figure 39-1. Discuss the role of anti-HBc IgM antibodies in the diagnosis of hepatitis B. How would you interpret a report in which the patient has anti-HBc IgG antibodies? Why would you not use anti-HBe antibody titers to diagnose an early infection?

5. Discuss how you would assess recurrent/novel infection with hepatitis B.

6. Discuss antiviral therapy for hepatitis B and hepatitis C.

7. The best treatment is avoidance (if possible) or immunization (for hepatitis B [not yet available for hepatitis C]).