Hepatitis D virus (delta) infection
Hepatitis D virus is a defective RNA virus that can only infect a person who also has hepatitis B, producing either simultaneous HBV-HDV co-infection, which can resolve, or superinfection of pre-existing chronic HBV, which carries a high risk of fulminant hepatitis and chronic liver disease. Diagnosis requires HBsAg positivity plus HDV IgG, treatment of progressive disease is 12 months of pegylated interferon with 25% to 45% cure, and definitive prevention is hepatitis B vaccination.
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What this article covers
- Overview
Hepatitis D virus (HDV, the delta agent) is a defective RNA virus that cannot replicate or produce infectious particles without concurrent hepatitis B virus (HBV) infection, because it depends on the…
- Epidemiology
HDV is endemic in the Mediterranean basin and Pacific islands, tracking the prevalence of chronic HBV in those regions.
- Risk factors
Chronic HBV infection is an absolute prerequisite; a person who is HBsAg-negative cannot acquire HDV.
- Pathophysiology
HDV cannot assemble infectious virions without HBV machinery: it uses the HBV surface antigen to form its envelope, making productive HDV infection entirely dependent on concurrent HBV infection.
- Clinical features
Presentation depends entirely on the HBV relationship: in simultaneous co-infection, the course ranges from inactive disease to acute hepatitis with jaundice, malaise, and right-upper-quadrant…
- Differential diagnosis
Hepatitis B virus infection alone (without HDV): confirmed by HBsAg positivity with negative HDV IgG; distinguishing this from co-infection or superinfection changes the expected severity and course; see hepatitis B virus infection.
- Diagnosis
HDV infection is confirmed by detecting HDV IgG in a patient who is HBsAg-positive; HDV testing is not interpretable, and should not be ordered, in a patient who has not first been confirmed HBsAg-positive.
- Management
Initially, determine whether the patient has evidence of progressive liver disease, since this threshold, not the mere presence of HDV IgG, determines whether antiviral therapy is warranted.
- Complications
Fulminant hepatitis from HDV superinfection: the most severe recognized outcome, occurring when HDV infects a patient with pre-existing chronic HBV; mandates urgent liver transplant center evaluation.
- Prognosis
Bimodal, dependent entirely on co-infection versus superinfection: simultaneous co-infection can resolve completely, while superinfection in a patient with chronic HBV carries materially higher risk…
- Prevention
Prevent hepatitis D by preventing hepatitis B: because HDV cannot infect a person without concurrent or prior HBV infection, hepatitis B vaccination in a nonimmune person eliminates HDV risk…
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Related articles
- Hepatitis B virus (HBV) infection
Hepatitis B virus is a bloodborne and sexually transmitted DNA virus that causes acute hepatitis and, when infection becomes chronic, progresses through immune-tolerant, immune-active, immune-control, and reactivation phases toward cirrhosis and hepatocellular carcinoma. Diagnosis rests on hepatitis B serology, chronic infection is treated with entecavir or tenofovir, and reactivation during immunosuppression is prevented with prophylactic antiviral therapy.
- Hepatitis C virus (HCV) infection
Hepatitis C virus is a bloodborne RNA virus, transmitted mainly by injection drug use, that produces mostly asymptomatic acute infection and chronic infection in 60% to 80% of cases. Diagnosis is by HCV antibody followed by HCV RNA, and direct-acting antiviral regimens cure more than 90% of patients, reducing but not eliminating the risk of cirrhosis and hepatocellular carcinoma.
- Hepatitis A virus infection
Hepatitis A virus is a fecal-oral RNA virus that causes acute, host-immune-mediated hepatitis with a prodrome followed by jaundice, aminotransferases often exceeding 1,000 U/L, and full recovery in at least 90% of patients within 3 to 6 months. Diagnosis rests on HAV IgM, treatment is supportive, and prevention centers on a 2-dose inactivated vaccine plus prompt postexposure prophylaxis.
- Hepatitis E virus infection
Hepatitis E virus is a fecal-oral or foodborne RNA virus with four genotypes that usually causes self-limited acute hepatitis resembling hepatitis A, but carries a high mortality risk in pregnant patients and can become chronic in immunocompromised hosts, especially solid-organ transplant recipients. Diagnosis rests on HEV IgM or RNA, treatment is supportive for acute disease and ribavirin for chronic infection, and prevention is safe water and thoroughly cooked pork or venison.