BASICS

Description

HBV is a DNA virus of the Hepadnaviridae family.
Transmission by blood, semen, vaginal secretions (horizontal and vertical).
Spectrum from acute hepatitis to chronic infection, cirrhosis, and hepatocellular carcinoma (HCC).

Epidemiology

Infects all ages; 80% cases aged 30–59 years.
US incidence ~3,000 confirmed new cases/year; estimated 20,000 unconfirmed.
Prevalence highest among Asian/Pacific Islanders.
Globally, ~296 million chronic HBV cases; >6 million children <5 years.
HBV causes ~820,000 deaths annually.
25% of chronic cases progress to liver cancer.

ETIOLOGY AND PATHOPHYSIOLOGY

Two transmission modes: horizontal (mucosal contact with infected fluids) and vertical (perinatal).
HBV DNA virus with multiple serologic markers guiding diagnosis and management.
Family history of HBV or HCC increases risk.

RISK FACTORS

Household or sexual contacts of HBV-infected individuals.
Birth in high-prevalence regions (Asia, Africa, Eastern Europe).
HIV or HCV coinfection.
Unvaccinated persons born in the US with endemic-area parents.
Chronic liver disease.
Pregnant women.
Blood product recipients, hemodialysis, immunosuppression.
Occupational exposure, body piercings/tattoos.
Injection drug use, sexual assault survivors.

PEDIATRIC AND PREGNANCY CONSIDERATIONS

Children have milder acute course; 90% perinatal infections become chronic.
Screen all pregnant women for HBsAg at first prenatal visit.
Treat high viral load or previous HBV-positive infant mothers starting at 28–32 weeks gestation.
Infants of HBV-positive mothers receive HBV vaccine and immune globulin within 12 hours of birth.
Breastfeeding is safe with appropriate neonatal prophylaxis.

PREVENTION

Vaccination series: 3 IM doses at 0, 1, and 6 months.
Vaccinate all medically stable infants ≥2,000 g within 24 hours of birth.
Vaccinate unvaccinated children, adults, high-risk groups, healthcare workers.
Postexposure prophylaxis: Hepatitis B immune globulin (HBIg) plus vaccination within 24 hours.
Safe sex practices, hygiene, needle precautions.

COMMONLY ASSOCIATED CONDITIONS

HIV and hepatitis C coinfection.
Extrahepatic manifestations: serum sickness-like syndrome, glomerulonephritis, polyarteritis nodosa, dermatologic disorders, cryoglobulinemia, Guillain-Barré syndrome.

DIAGNOSIS

History

Acute: fever, fatigue, arthralgias, myalgias, anorexia, nausea, vomiting, RUQ pain, jaundice, dark urine.
Chronic: often asymptomatic.

Physical Exam

Stigmata of chronic liver disease: jaundice, hepatomegaly, palmar erythema, ascites, spider nevi, encephalopathy.

Differential Diagnosis

Other viral hepatitis (A, C, D, E), EBV, CMV.
Drug-induced, alcoholic, autoimmune hepatitis.
Wilson disease, hemochromatosis, HIV.

Laboratory and Imaging

AST/ALT markedly elevated in acute HBV (ALT > AST).
Transaminases normal or mildly elevated in chronic HBV.
Bilirubin elevated in acute infection.
HBcAb IgM early marker in “window period.”
HBeAg positivity correlates with high viral replication.
Screen for HDV, HIV, HCV.
Ultrasound for portal hypertension, HCC surveillance.

Serologic Markers

Marker	Acute Infection	Chronic Infection	Inactive Carrier	Resolved Infection	Susceptible	Vaccinated
HBsAg	+	+	+	-	-	-
Anti-HBs	-	-	-	+	-	+
Anti-HBc IgM	+	-	-	+ (total/IgG)	-	-
HBeAg	+	±	-	-	-	-
Anti-HBe	-	±	+	±	-	-
HBV DNA	Present	Present	Low/Negative	-	-	-
ALT	Markedly elevated	Normal to mildly elevated	Normal	Normal	Normal	Normal

TREATMENT

General Measures

Vaccinate seronegative patients.
Monitor CBC, coagulation, electrolytes, glucose, renal function.
Screen HBsAg-positive patients for HCC routinely.

Acute HBV

Supportive care; resolves spontaneously in ~95% immunocompetent adults.
Antivirals reserved for fulminant liver failure or immunosuppressed patients.
Options: tenofovir or entecavir monotherapy.

Chronic HBV

Treatment guided by HBeAg status, HBV DNA, ALT, and fibrosis.
First-line agents: entecavir, tenofovir (preferred).
Pegylated interferon α2a or α2b for selected patients.
Treatment duration:
HBeAg-positive: continue 6–12 months after seroconversion.
HBeAg-negative: indefinite or until seroconversion.
Adjust therapy for resistance; confirm adherence before changing meds.

ISSUES FOR REFERRAL

Hepatology for persistent HBsAg positivity.
Fulminant hepatitis, end-stage liver disease, or HCC.
Liver transplantation evaluation.

SURGERY/OTHER PROCEDURES

Liver transplant for liver failure.
Resection or ablation for hepatocellular carcinoma.

ONGOING CARE

Monitor ALT and HBV DNA every 3–6 months during therapy.
Ultrasound and α-fetoprotein every 6–12 months for HCC surveillance starting age 40 (men), 50 (women).
Counsel on alcohol avoidance and medication compliance.

DIET

Avoid alcohol; increases risk of cirrhosis and HCC.

PATIENT EDUCATION

Explain transmission precautions.
Emphasize vaccination and medication adherence.
Counsel on risk of transmission to contacts.

PROGNOSIS

5-year cirrhosis risk: ~8–20% untreated chronic HBV.
2–5% risk of HCC development, with or without cirrhosis.

COMPLICATIONS

Hepatic necrosis, cirrhosis, hepatic failure.
Hepatocellular carcinoma.
Reactivation with immunosuppression.
Severe flares with corticosteroids or immunosuppressants.

REFERENCES

Schillie S, Vellozzi C, Reingold A, et al. Prevention of hepatitis B virus infection in the United States: recommendations of the Advisory Committee on Immunization Practices. MMWR Recomm Rep. 2018;67(1):1-31.
Wilkins T, Sams R, Carpenter M. Hepatitis B: screening, prevention, diagnosis, and treatment. Am Fam Physician. 2019;99(5):314-323.

ADDITIONAL READING

CDC. 2019 Viral hepatitis surveillance report. https://www.cdc.gov/hepatitis/statistics/2019surveillance/index.htm

Clinical Pearls: - Screen all patients born in HBV-endemic countries using HBsAg. - Chronic HBV: HBsAg persistence >6 months; lifelong monitoring required. - Acute HBV diagnosed with HBsAg and IgM anti-HBc; mainly supportive treatment. - Antiviral therapy based on cirrhosis status, ALT, and HBV DNA levels.