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Hepatitis — A Complete Guide
Hepatitis means inflammation of the hepatic parenchyma. It can be caused by viruses (the most common cause), alcohol, drugs/toxins, autoimmune disease, or metabolic disorders.
1. Overview of Causes
| Category | Examples |
|---|---|
| Viral | HAV, HBV, HCV, HDV, HEV; also EBV, CMV, HSV |
| Alcoholic | Alcohol-induced steatohepatitis |
| Drug/Toxin | Isoniazid, acetaminophen, many others |
| Autoimmune | Autoimmune hepatitis (AIH) |
| Metabolic | NAFLD/NASH, Wilson disease, hemochromatosis |
2. General Clinical Features of Acute Hepatitis
All forms of acute hepatitis share a common presentation:
- Prodrome: low-grade fever, fatigue, anorexia, nausea/vomiting, RUQ pain, arthralgias/myalgias
- Icteric phase: dark urine, jaundice, clay-colored stools
- Labs: elevated bilirubin, ↑↑ transaminases (ALT > AST in viral; AST > ALT in alcoholic), elevated ALP
Alarm features (severe hepatic failure): mental status changes (hepatic encephalopathy), asterixis, ascites, prolonged PT/INR → require hospitalization and liver transplant evaluation.
Most cases of acute hepatitis resolve without complications and can be managed as outpatients, though symptomatic improvement precedes normalization of LFTs. — Textbook of Family Medicine 9e
3. Viral Hepatitis A–E
🅐 Hepatitis A (HAV)
| Feature | Details |
|---|---|
| Virus | Picornavirus (ssRNA, non-enveloped) |
| Transmission | Fecal-oral (contaminated food/water) |
| Incubation | 2–6 weeks |
| Chronicity | None — always self-limited, no carrier state |
| Immunity | Anti-HAV IgG confers lifelong immunity |
| Vaccine | Yes — formalin-inactivated, highly effective, licensed since 1995 |
Serology timeline:
- Fecal HAV shedding peaks before symptoms
- IgM anti-HAV: acute infection marker (positive at symptom onset, resolves < 1 year)
- IgG anti-HAV: past infection / vaccine immunity (lifelong)
Post-exposure prophylaxis: Immune globulin (IG) within 1–2 weeks of exposure is ~90% effective. HAV vaccine is preferred for pre-exposure and provides more durable immunity.
🅑 Hepatitis B (HBV)
| Feature | Details |
|---|---|
| Virus | Hepadnavirus (dsDNA, enveloped) |
| Transmission | Parenteral, sexual, vertical (mother-to-child) |
| Incubation | 4–20 weeks |
| Chronicity | ~90% of neonates; ~5–10% of adults |
| Vaccine | Yes — recombinant HBsAg, 3-dose schedule |
Serology timeline:
HBV Serology Interpretation Table (Jawetz Medical Microbiology)
| HBsAg | Anti-HBs | Anti-HBc | Interpretation |
|---|---|---|---|
| ✅ | ❌ | ❌ | Early acute HBV — confirm to exclude nonspecific reactivity |
| ✅ | ± | ✅ | Acute or chronic HBV — differentiate with IgM anti-HBc |
| ❌ | ✅ | ✅ | Past HBV infection — immune |
| ❌ | ❌ | ✅ | Past infection / low-level carrier / "window period" — check IgM anti-HBc + HBV DNA |
| ❌ | ❌ | ❌ | Never infected |
| ❌ | ✅ | ❌ | Successful vaccination |
Key antigens:
- HBsAg: first marker to appear; persists >6 months = chronic carrier
- HBeAg: marker of high replicative activity / high infectivity
- Anti-HBe: seroconversion = lower infectivity, sign of resolving infection
- IgM anti-HBc: best test for acute infection (short-lived, 3–6 weeks)
Vertical transmission risk:
- Mother HBsAg+ only: ~10–20% transmission
- Mother HBsAg+ and HBeAg+: ~90% transmission without prophylaxis
- Neonatal infection → 85–95% risk of chronic HBV
Treatment (chronic HBV): Indicated for chronic active hepatitis to prevent fibrosis progression and HCC.
- First-line: pegylated interferon alfa-2a, entecavir, tenofovir (preferred in pregnancy)
- Entecavir: guanosine analogue — 67% undetectable HBV DNA (HBeAg+), 90% (HBeAg–)
- Tenofovir: nucleotide analogue — 76% (HBeAg+), 93% (HBeAg–)
- Second-line: telbivudine; third-line: lamivudine, adefovir
🅒 Hepatitis C (HCV)
| Feature | Details |
|---|---|
| Virus | Flavivirus (ssRNA, enveloped), 6 genotypes |
| Transmission | Parenteral (IV drug use, needlestick); sexual (less efficient) |
| Incubation | ~6–12 weeks |
| Chronicity | ~70–85% become chronic |
| Vaccine | None available |
Natural history — chronic HCV:
HCV RNA persists throughout (detectable from very early after infection). Anti-HCV rises ~3–12 months after exposure but does not confer immunity or indicate resolution. The characteristic "sawtooth" ALT pattern reflects episodic hepatic injury as disease progresses from acute → chronic active hepatitis → cirrhosis → HCC over decades.
Diagnosis:
- Anti-HCV: detects antibody (50–70% positive at symptom onset; lag of 3–6 weeks in others)
- HCV RNA by RT-PCR: confirms active infection; used for monitoring treatment
Treatment (modern era — direct-acting antivirals):
Direct-acting antiviral regimens using nucleoside inhibitors have revolutionized hepatitis treatment. — Rosen's Emergency Medicine
- Sofosbuvir (NS5B RNA polymerase inhibitor) + simeprevir (NS3/4A protease inhibitor): >90% sustained virological response (SVR)
- Interferon-free regimens now available with far less toxicity
- SVR = "functional cure" (undetectable HCV RNA 12 weeks after treatment end)
- Old standard (pegIFN + ribavirin): 30–35% SVR for genotype 1; 75–80% for genotypes 2/3
🅓 Hepatitis D (HDV) — "Delta Hepatitis"
| Feature | Details |
|---|---|
| Virus | Defective RNA virus — requires HBsAg to replicate |
| Transmission | Same as HBV (parenteral, sexual) |
| Forms | Coinfection (HAV + HBV simultaneous) vs. Superinfection (HDV in chronic HBV carrier) |
| Severity | Superinfection → more severe; ~70–80% progress to chronic disease |
| Prevention | HBV vaccination prevents HDV (HDV cannot exist without HBV) |
Coinfection (acute HBV + acute HDV): usually self-limited; low risk of chronic disease.
Superinfection (HDV in chronic HBV carrier): higher risk of fulminant hepatitis and cirrhosis.
🅔 Hepatitis E (HEV)
| Feature | Details |
|---|---|
| Virus | Hepevirus (ssRNA, non-enveloped), genotypes 1–4 |
| Transmission | Fecal-oral (genotypes 1 & 2 — developing world); zoonotic pork/game (genotypes 3 & 4 — developed world) |
| Incubation | ~2–8 weeks |
| Chronicity | Rare in immunocompetent; can be chronic in immunosuppressed (genotype 3) |
| Special danger | Pregnant women — mortality 5–25% (2nd/3rd trimester) — highest risk of acute liver failure |
| Vaccine | Available in China (not globally licensed) |
Clinical features resemble HAV. Most cases are self-limited. Neurologic manifestations (Guillain-Barré-like) are the most common extrahepatic feature with genotype 3.
4. Hepatitis Types at a Glance
| HAV | HBV | HCV | HDV | HEV | |
|---|---|---|---|---|---|
| Genome | ssRNA | dsDNA | ssRNA | ssRNA | ssRNA |
| Route | Fecal-oral | Parenteral/sexual/vertical | Parenteral | Parenteral/sexual | Fecal-oral |
| Incubation | 2–6 wk | 4–20 wk | 6–12 wk | 3–7 wk | 2–8 wk |
| Chronicity | None | ~5–10% (adults) | ~70–85% | ~70–80% (superinfection) | Rare (immunocompetent) |
| Fulminant | Rare | Rare | Very rare | Superinfection | Pregnant women |
| Vaccine | ✅ | ✅ | ❌ | (via HBV vaccine) | Limited |
5. Alcoholic Hepatitis
- Spectrum: steatosis → steatohepatitis → cirrhosis → HCC
- Labs: transaminases elevated but milder than viral hepatitis; AST:ALT ratio > 2:1 (classic)
- Hypoglycemia: common (depleted glycogen + suppressed gluconeogenesis)
- Severity scoring: Maddrey Discriminant Function (MDF) = 4.6 × (PT − control) + total bilirubin
- MDF > 32 = severe → prednisone 40 mg/day or methylprednisolone 32 mg IV/day
6. Other Non-Viral Causes
- Drug-induced: isoniazid, acetaminophen (acetaminophen overdose → treat immediately with N-acetylcysteine)
- Autoimmune hepatitis: positive ANA, anti-smooth muscle Ab (ASMA), elevated IgG; treat with prednisone ± azathioprine
- NAFLD/NASH: metabolic syndrome association; may progress to cirrhosis without viral etiology
7. Complications of Chronic Hepatitis
Any chronic hepatitis (B, C, alcoholic, autoimmune) can progress to:
- Cirrhosis → portal hypertension → ascites, varices, splenomegaly
- Hepatic encephalopathy (↑ ammonia)
- Hepatorenal syndrome (rising creatinine in liver failure)
- Hepatocellular carcinoma (HCC) — especially with HBV and HCV
8. Prevention Summary
| Agent | Vaccine | Post-Exposure Prophylaxis |
|---|---|---|
| HAV | ✅ Inactivated vaccine | Immune globulin (within 2 weeks) or HAV vaccine |
| HBV | ✅ Recombinant HBsAg (3 doses) | HBIG + HBV vaccine simultaneously |
| HCV | ❌ | None (no prophylaxis available) |
| HDV | (HBV vaccine protects) | — |
| HEV | Limited (China) | None globally available |
Sources
- Jawetz, Melnick & Adelberg's Medical Microbiology, 28th Ed.
- Sleisenger and Fordtran's Gastrointestinal and Liver Disease
- Harrison's Principles of Internal Medicine, 21st Ed. (serology figures)
- Textbook of Family Medicine, 9th Ed.
- Rosen's Emergency Medicine
- Goldman-Cecil Medicine
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