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ESSENTIALS OF DIAGNOSIS
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ESSENTIALS OF DIAGNOSIS
Hepatitis A and E, which are transmitted by the fecal-oral route, are self-limited and rarely cause chronic infection.
Hepatitis B, C, and D are acquired percutaneously or sexually; all can result in chronic infection.
Infection with hepatitis D occurs only in a host with concurrent hepatitis B.
All five hepatitis viruses can cause acute liver failure.
Diagnostic tests appropriate to different clinical situations detect specific viral antigens and antibodies in serum by sensitive immunoassay, and viral DNA/RNA by sensitive amplification assays (eg, polymerase chain reaction [PCR]).
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General Considerations
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Although hepatitis viruses have been characterized extensively, knowledge of the pathogenesis, diagnosis, and treatment of chronic viral hepatitis continues to evolve. Sensitive and specific assays are available for all five forms (A–E) of viral hepatitis (Table 41–1). Nevertheless, approximately 5–10% of cases of apparent acute infectious hepatitis are unable to be attributed to any of the readily identifiable viral hepatidities, and nearly 50% of cases of acute liver failure cannot be attributed to a specific cause. Whether additional unidentified viruses cause acute or chronic liver disease remains an unanswered question. This chapter focuses on clinical features of the five known hepatitis viruses, hepatitis A through E, that are responsible for the majority of recognized cases of acute and chronic viral hepatitis (Table 41–2).
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