What are the differences in presentation, diagnosis, and treatment of viral hepatitis A and hepatitis B?

Presentation, Diagnosis, and Treatment of Viral Hepatitis A and B

Clinical Presentation

Hepatitis A

Hepatitis A presents with acute viral hepatitis symptoms but cannot be distinguished from other forms of viral hepatitis on clinical presentation alone, requiring serologic confirmation. 1

• Maximal viral excretion occurs before the onset of jaundice, making early transmission common 2
• Typically causes acute self-limiting hepatitis without chronic infection 3
• 10-15% of patients experience relapsing illness 1
• Some patients may progress to acute liver failure 1
• Transmission occurs primarily via the enteric (fecal-oral) route 2

Hepatitis B

Acute HBV infection is asymptomatic in 60-70% of patients, making clinical diagnosis unreliable without serologic testing. 1

• When symptomatic, presents with signs and symptoms of acute viral hepatitis indistinguishable from other hepatitides 1
• More than 95% of adults with acute HBV recover spontaneously without treatment 4
• Can progress to chronic infection (persistence of HBsAg beyond 6 months) 1
• Chronic infection carries risk of cirrhosis and hepatocellular carcinoma 1
• Transmission occurs through blood, sexual contact, and perinatal exposure 1

Diagnosis

Hepatitis A Diagnosis

Diagnosis requires positive IgM antibody to HAV in persons with clinical signs or symptoms of acute viral hepatitis. 1

• IgM anti-HAV is the definitive diagnostic marker 1
• Serologic confirmation is mandatory as clinical presentation alone is insufficient 1

Hepatitis B Diagnosis

Acute HBV infection is diagnosed by detection of HBsAg and IgM anti-HBc (without total anti-HBc initially). 1, 4

Key serologic patterns:

• Acute infection: HBsAg positive + IgM anti-HBc positive 1
• Chronic infection: HBsAg persistence beyond 6 months + total anti-HBc positive (usually IgM anti-HBc negative) 1
• Resolved infection: HBsAg negative + anti-HBs positive + total anti-HBc positive 1
• Isolated IgM anti-HBc may indicate acute infection during the window period between HBsAg disappearance and anti-HBs development 1

Important caveat: IgM anti-HBc can appear during acute exacerbations of chronic hepatitis B, making differentiation from true acute infection challenging 5. This distinction is critical because management strategies differ significantly 5.

Additional testing for chronic HBV:

• HBV DNA quantification to assess viral replication 1
• HBeAg and anti-HBe status 1
• ALT levels and liver function tests 1
• Baseline ultrasound for HCC screening in all HBsAg-positive persons ≥20 years 1
• Consider liver biopsy or transient elastography to assess fibrosis in patients with elevated ALT 1

Treatment

Hepatitis A Treatment

Management of hepatitis A is entirely supportive, as no specific antiviral therapy exists or is needed. 1

• Rest, hydration, and symptomatic relief 1
• Monitor for progression to acute liver failure (rare) 1
• No antiviral medications indicated 1

Hepatitis B Treatment

Acute Hepatitis B

The vast majority of acute HBV cases require no treatment, as spontaneous recovery occurs in >95% of adults. 4

Treatment is indicated ONLY for severe acute hepatitis B, defined as: 4

• Coagulopathy (INR ≥1.5) 4
• Protracted course (persistent symptoms or marked jaundice >4 weeks) 4
• Signs of acute liver failure 4

For severe cases, nucleos(t)ide analogues (NAs) are the treatment of choice, with entecavir or tenofovir preferred due to potent viral suppression and low resistance rates. 4

Treatment duration for severe acute HBV:

• Continue for at least 3 months after seroconversion to anti-HBs, OR 4
• At least 12 months after anti-HBe seroconversion without HBsAg loss 4

Critical pitfall: Do not delay treatment in patients with signs of severe acute hepatitis B or liver failure. 4 Patients with fulminant or severe hepatitis must be evaluated for liver transplantation. 4

Chronic Hepatitis B

Long-term administration of a potent nucleos(t)ide analogue with high barrier to resistance—entecavir, tenofovir disoproxil, or tenofovir alafenamide—represents the treatment of choice for chronic HBV. 1

FDA-approved therapies include: 1

• Interferon alfa-2b
• Peginterferon alfa-2a
• Lamivudine
• Adefovir dipivoxil
• Entecavir
• Telbivudine
• Tenofovir disoproxil fumarate

Treatment indications for chronic HBV: 1

• HBV DNA ≥2,000 IU/mL
• Elevated ALT
• At least moderate histological lesions
• All cirrhotic patients with detectable HBV DNA should be treated regardless of other factors 1

Peginterferon alfa can be considered in mild to moderate chronic hepatitis B patients, but is contraindicated in decompensated liver disease. 4

Treatment goals and monitoring:

• Main goal: Long-term suppression of HBV replication to prevent disease progression and HCC 1
• Optimal endpoint: HBsAg loss 1
• Serologic endpoints: Loss of HBeAg, HBeAg seroconversion, suppression of HBV DNA to undetectable levels, loss of HBsAg 1
• Lifelong monitoring required even in treated patients to assess disease progression and HCC risk 1

Important resistance considerations:

• Lamivudine resistance occurs in up to 70% during first 5 years 1
• Lower resistance with adefovir (30% in 5 years), entecavir (<1% at 4 years), telbivudine (2.3-5% in 1 year) 1
• Combination therapies are not generally recommended 1

Prevention Strategies

Hepatitis A prevention: 1

• Two doses of hepatitis A vaccine 6-18 months apart
• All chronic HBV patients lacking HAV immunity should be vaccinated 1

Hepatitis B prevention: 1

• Universal infant vaccination 1
• Vaccination of all adolescents not previously vaccinated 1
• Vaccination of adults in high-risk groups 1
• Maternal screening and postexposure prophylaxis for newborns of HBsAg-positive mothers 1
• Vaccination of sexual and household contacts of HBsAg-positive persons 1

Critical warning for HBV patients: Severe acute exacerbations of hepatitis have been reported in HBV-infected patients who discontinue tenofovir or other antivirals. 6 Never discontinue treatment without physician consultation. 6