Hepatitis C

Hepatitis C – High‑Yield Study Guide for Medical Students

Definition

Hepatitis C is a systemic viral infection caused by the hepatitis C virus (HCV), an enveloped, positive-sense single-stranded RNA flavivirus that primarily targets hepatocytes, leading to acute and chronic hepatitis, progressive fibrosis, cirrhosis, hepatocellular carcinoma (HCC), and extrahepatic manifestations.

Epidemiology

Hepatitis C is a major global cause of chronic liver disease and liver-related mortality.

• Global burden: An estimated 58 million people worldwide have chronic HCV infection, with ~1.5 million new infections annually.^[1]
• Transmission routes: Primarily via percutaneous exposure to infected blood (injection drug use, unsafe medical injections, transfusions before routine screening), less commonly via sexual transmission and perinatally.^[1]
• Risk groups: People who inject drugs (PWID), recipients of blood products before early 1990s (in high-income countries), hemodialysis patients, HIV-positive individuals, men who have sex with men with high-risk sexual practices, and infants of HCV-infected mothers.^[1]
• Genotypes: Multiple genotypes (1–6, plus subtypes); genotype distribution varies by region, but direct-acting antiviral (DAA) regimens now often cover all genotypes (pangenotypic).

Pathophysiology

HCV is hepatotropic, but the liver injury is largely immune mediated rather than purely cytopathic.

• Viral entry and replication: HCV enters hepatocytes via cell surface receptors (e.g., CD81, scavenger receptor class B type I) and replicates in the cytoplasm using an RNA-dependent RNA polymerase lacking proofreading, promoting high genetic variability and quasi-species formation.^[2]
• Immune response: Innate and adaptive immune responses are triggered. Ineffective viral clearance and viral immune evasion (e.g., rapid mutation, interference with interferon signaling) result in chronic infection in ~55–85% of acutely infected individuals.^[2]
• Chronic inflammation and fibrosis: Persistent infection leads to chronic hepatic inflammation, activation of Kupffer cells and hepatic stellate cells, and deposition of extracellular matrix, producing progressive fibrosis and eventually cirrhosis.
• Carcinogenesis: Cirrhosis and ongoing inflammation promote genomic instability, oxidative stress, and dysregulated regenerative nodules, increasing risk of hepatocellular carcinoma (HCC) even after viral clearance (though risk is reduced).
• Extrahepatic manifestations: HCV infects lymphocytes and triggers immune complexes, leading to mixed cryoglobulinemia, membranoproliferative glomerulonephritis, B‑cell lymphomas, and various autoimmune and metabolic complications.

Clinical Presentation

Clinical features differ between acute and chronic HCV infection and many patients are asymptomatic until advanced disease.

Acute Hepatitis C

• Incubation period: Typically 2–12 weeks after exposure.
• Symptoms:
  • Often asymptomatic or mild, nonspecific symptoms (fatigue, anorexia, nausea, myalgias, low-grade fever).
  • Less commonly, features of acute hepatitis: right upper quadrant discomfort, dark urine, jaundice, pruritus.
• Laboratory findings: Elevated ALT/AST (often ALT > AST), with possible hyperbilirubinemia and elevated INR in severe cases.
• Spontaneous clearance: Occurs in ~15–45% of acutely infected individuals within 6 months, more likely in females, those with symptomatic acute hepatitis, and some host genetic backgrounds.

Chronic Hepatitis C

• Definition: Persistence of HCV RNA for >6 months after acute infection.
• Symptoms:
  • Most are asymptomatic for years.
  • Nonspecific: chronic fatigue, malaise, mild right upper quadrant discomfort.
• Signs of chronic liver disease (if advanced):
  • Jaundice, spider angiomata, palmar erythema, gynecomastia, testicular atrophy.
  • Ascites, hepatic encephalopathy, edema, muscle wasting.
  • Splenomegaly, caput medusae, variceal bleeding (features of portal hypertension).
• Extrahepatic manifestations:
  • Mixed cryoglobulinemic vasculitis: palpable purpura, arthralgias, weakness, peripheral neuropathy.
  • Renal disease: membranoproliferative glomerulonephritis (proteinuria, hematuria, nephritic/nephrotic syndrome).
  • Dermatologic: lichen planus, porphyria cutanea tarda.
  • Endocrine/metabolic: insulin resistance, type 2 diabetes, thyroid disorders.
  • Hematologic/oncologic: B‑cell non-Hodgkin lymphoma, cryoglobulinemia, thrombocytopenia.

Diagnosis

Diagnosis relies on serologic screening and confirmatory nucleic acid testing, followed by assessment of liver disease severity and comorbidities.

Screening and Initial Testing

• Who to screen:
  • All adults at least once in their lifetime in many guideline systems, with periodic testing for ongoing risk (e.g., PWID, hemodialysis, HIV-positive).^[3]
  • Pregnant women in many settings (universal or risk-based screening).
  • People with abnormal liver enzymes, history of transfusion before screening era, or other risk factors.
• Screening test: Anti-HCV antibody (third-generation ELISA) is the standard initial test.

Diagnostic Algorithm

• Step 1 – Anti-HCV antibody:
  • Negative: Usually no current infection, but consider early window period in recent high-risk exposure; if high suspicion, perform HCV RNA or repeat antibody later.
  • Positive: Indicates current or past infection. Requires confirmatory RNA testing.
• Step 2 – HCV RNA (quantitative or qualitative PCR):
  • Detectable HCV RNA: Confirms active infection (acute or chronic).
  • Undetectable HCV RNA: Indicates resolved infection (spontaneous or treatment-induced) or false-positive antibody test.
• Step 3 – Chronicity: Persistence of detectable HCV RNA >6 months defines chronic infection.

Pre-treatment Evaluation

• Assess liver disease severity:
  • Serum ALT/AST, bilirubin, albumin, INR, platelet count.
  • Non-invasive fibrosis scores (e.g., FIB-4, APRI) and transient elastography (FibroScan) to stage fibrosis and identify cirrhosis.
• Identify HCV genotype: Still relevant if non-pangenotypic regimen is being considered, though many first-line regimens are pangenotypic.
• Screen for co-infections and comorbidities:
  • HIV, hepatitis B (HBsAg, anti-HBc, anti-HBs) to anticipate HBV reactivation risk.
  • Assess renal function (eGFR), glucose, lipids, and pregnancy status where appropriate.
• HCC and varices screening (if cirrhosis):
  • Baseline abdominal ultrasound (± alpha-fetoprotein) for HCC surveillance.
  • Upper endoscopy to assess for esophageal varices depending on local protocols.

Management

Modern management focuses on highly effective oral direct-acting antiviral (DAA) regimens, plus comprehensive care for liver disease and extrahepatic manifestations.

Treatment Goals

• Virologic goal: Achieve sustained virologic response (SVR), defined as undetectable HCV RNA 12 weeks after completion of therapy (SVR12), which is considered a virologic cure.^[3]
• Clinical goals: Halt progression of fibrosis, reduce risk of cirrhosis and decompensation, reduce incident HCC, improve quality of life, and decrease extrahepatic manifestations and transmission.

Direct-Acting Antiviral (DAA) Therapy

Regimens and durations depend on genotype, presence of cirrhosis, prior treatment, and comorbidities. Most are once-daily oral combinations taken for 8–12 weeks with cure rates >95%.

• Pangenotypic first-line regimens (examples):
  • Sofosbuvir/velpatasvir: Typically 12-week regimen; avoid sofosbuvir in severe renal impairment (eGFR <30 mL/min) unless specific guidance.
  • Glecaprevir/pibrentasvir: Often 8-week regimen for non-cirrhotics and selected compensated cirrhotics; not used in decompensated cirrhosis due to protease inhibitor component.
• Genotype-specific regimens: Used in specific circumstances where pangenotypic options are unavailable or not suitable.
• Resistance testing: Considered in some retreatment and specific NS5A-containing regimens; less critical with pangenotypic high-barrier regimens.
• Monitoring during therapy:
  • Baseline and on-treatment liver function tests, renal function, and HCV RNA according to local protocols.
  • Assess for adverse effects: DAAs are generally well tolerated (fatigue, headache, mild GI symptoms most common).
  • In HBV coinfection, monitor for HBV reactivation; prophylactic HBV therapy may be required.
• Post-treatment follow-up:
  • Confirm SVR12 with HCV RNA at 12 weeks after completion of therapy.
  • In patients without cirrhosis who achieve SVR, routine liver-related follow-up is minimal beyond standard care and risk factor management.
  • In patients with cirrhosis, continue lifelong HCC surveillance and cirrhosis management; SVR reduces but does not eliminate HCC risk.

Management of Liver Disease and Complications

• Cirrhosis care:
  • Standard cirrhosis management: sodium restriction and diuretics for ascites, nonselective beta-blockers and/or endoscopic band ligation for variceal prophylaxis, lactulose (± rifaximin) for encephalopathy, vaccinations (HBV, HAV, pneumococcal, influenza).
  • Regular surveillance for HCC with ultrasound ± AFP every 6 months.
• End-stage liver disease: Refer for liver transplant evaluation in decompensated cirrhosis or HCC meeting transplant criteria; many candidates now receive DAAs either pre- or post-liver transplantation.
• Extrahepatic manifestations:
  • HCV cure often improves cryoglobulinemia, renal disease, and other extrahepatic manifestations.
  • Additional therapy (e.g., immunosuppression, plasmapheresis) may be required for severe vasculitis or glomerulonephritis.

Prevention and Public Health

• No vaccine: There is currently no licensed HCV vaccine; prevention relies on harm reduction and infection control.
• Primary prevention:
  • Safe injection practices, needle and syringe programs, opioid substitution therapy.
  • Rigorous blood donor screening and safe medical procedures.
  • Safe sex practices, particularly in high-risk populations.
• Secondary prevention:
  • Widespread screening programs to identify and treat people with chronic infection and reduce transmission.
  • Linkage to care and retention in care, especially among marginalized populations (PWID, prisoners).
• Mother-to-child transmission:
  • Chronic maternal HCV carries a 5–10% transmission risk; higher with uncontrolled HIV coinfection.
  • Elective cesarean section is not routinely recommended solely for HCV; breastfeeding is generally allowed unless nipples are cracked/bleeding.

Key Clinical Pearls and Exam Tips

• 1. Chronicity is the rule: Most HCV infections become chronic (about 55–85%); many patients are asymptomatic for years, so screening is critical.
• 2. Diagnosis requires RNA: A positive anti-HCV antibody alone only indicates exposure. Active infection is confirmed by detectable HCV RNA.
• 3. ALT patterns: In chronic HCV, ALT may be intermittently elevated or even normal despite ongoing histologic activity; normal ALT does not exclude significant disease.
• 4. DAAs have revolutionized therapy: Modern oral regimens achieve >95% cure in 8–12 weeks, with few contraindications and limited side effects, and are now standard of care.^[3]
• 5. Cirrhosis and HCC risk: Chronic HCV is a leading cause of cirrhosis and HCC. Even after SVR, cirrhotic patients remain at ongoing HCC risk and require lifelong surveillance.
• 6. Extrahepatic manifestations: Think HCV in patients with mixed cryoglobulinemic vasculitis, unexplained MPGN, lichen planus, porphyria cutanea tarda, or certain B-cell lymphomas.
• 7. Coinfections matter: HIV and HBV coinfection accelerate fibrosis progression and modify management (e.g., HBV reactivation risk when starting DAAs).
• 8. Exam tip – transfusion era: For board questions, a patient with chronic liver disease who received blood transfusions before early 1990s or a history of injection drug use is classic for chronic HCV.

References

• 1. World Health Organization. (2022). Hepatitis C. https://www.who.int/news-room/fact-sheets/detail/hepatitis-c
• 2. Thomas, D. L. (2013). Global control of hepatitis C: where challenge meets opportunity. Nature Medicine, 19(7), 850–858. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4100823/
• 3. American Association for the Study of Liver Diseases & Infectious Diseases Society of America. (Updated regularly). HCV Guidance: Recommendations for Testing, Managing, and Treating Hepatitis C. https://www.hcvguidelines.org/