Overview
Definition:
Hepatitis B virus (HBV) infection is a significant global public health problem, particularly in regions with high endemicity
Adoptees and immigrants from such areas may have a higher prevalence of chronic HBV infection, necessitating targeted screening strategies in pediatric practice
Chronic HBV infection can lead to serious liver disease, including cirrhosis and hepatocellular carcinoma.
Epidemiology:
Globally, an estimated 296 million people were living with chronic HBV infection in 2019, with the majority residing in the Western Pacific and African regions
Countries with high endemicity (HBsAg prevalence >8%) include many in Asia, Africa, and parts of Eastern Europe and South America
Children adopted from or immigrating from these regions are at increased risk of HBV infection acquired perinatally or in early childhood.
Clinical Significance:
Inadequate screening and management of HBV in pediatric adoptees and immigrants can lead to the silent progression of chronic liver disease, potentially resulting in irreversible liver damage and increased morbidity and mortality
Early identification and appropriate management are crucial for preventing long-term complications and reducing HBV transmission.
Screening Recommendations
Indications For Screening:
All children adopted internationally from countries with high or intermediate HBV endemicity should be screened for HBV infection
Screening should also be considered for children immigrating from these regions, especially if their vaccination status is unknown or incomplete or if they have specific risk factors.
Recommended Tests:
The recommended screening panel includes Hepatitis B surface antigen (HBsAg), Hepatitis B surface antibody (anti-HBs), and Hepatitis B core antibody (anti-HBc)
Testing for HBV DNA is indicated in individuals with a positive HBsAg or those with specific clinical scenarios.
Timing Of Screening:
Screening should ideally be performed shortly after arrival in the new country or as part of routine health evaluations
For children with potential exposure, testing may be repeated at follow-up intervals based on clinical risk assessment.
Interpretation Of Results:
Positive HBsAg indicates current HBV infection (acute or chronic)
Presence of anti-HBs with negative HBsAg and anti-HBc suggests successful vaccination or recovery from past infection
Isolated anti-HBc can indicate past infection without detectable surface antigen or antibody, or a false positive
HBV DNA testing may be useful in select cases.
Clinical Presentation In Children
Acute Hepatitis B:
Many children with acute HBV infection are asymptomatic
When symptoms occur, they may include fever, malaise, anorexia, nausea, vomiting, abdominal pain, and jaundice
Dark urine and pale stools may also be present
Fulminant hepatitis is rare but can be life-threatening.
Chronic Hepatitis B:
Chronic HBV infection in children is often asymptomatic for years or decades
When symptoms do appear, they may be non-specific, such as fatigue or abdominal discomfort
Physical examination findings may be normal or may reveal hepatomegaly or signs of advanced liver disease (e.g., jaundice, ascites, splenomegaly) in later stages.
Risk Of Chronicity:
The risk of developing chronic HBV infection is inversely related to the age at infection
Perinatal transmission leads to a >90% risk of chronicity, while infection in children aged 1-5 years has a 30-50% risk
Children infected after age 5 years have a <10% risk of chronicity.
Diagnostic Approach
History Taking:
Detailed history of travel to or origin from endemic regions
Information on prior HBV vaccination status, exposure to HBV-infected individuals, blood transfusions, surgical procedures, and perinatal transmission risk
Family history of liver disease or HBV infection
Ask about any signs or symptoms suggestive of liver disease.
Physical Examination:
A thorough physical examination is essential
Assess for jaundice (scleral icterus, skin), hepatomegaly, splenomegaly, ascites, and signs of chronic liver disease like palmar erythema, spider angiomata, or gynecomastia
Assess growth parameters and nutritional status.
Serological Markers:
HBsAg, anti-HBs, anti-HBc (total and IgM)
HBV DNA quantification is crucial for assessing viral replication and guiding treatment decisions
Liver function tests (ALT, AST, bilirubin, albumin, prothrombin time/INR) provide information on liver inflammation and synthetic function.
Imaging Studies:
Abdominal ultrasound is useful for evaluating liver size and echotexture, assessing for steatosis, cirrhosis, portal hypertension, and detecting hepatic masses
Transient elastography (FibroScan) can assess liver stiffness and stage fibrosis.
Management Of Hepatitis B In Pediatrics
Indications For Antiviral Therapy:
Antiviral therapy is generally indicated for children with chronic HBV infection who have evidence of significant liver inflammation (elevated ALT levels), liver fibrosis, or high viral load (HBV DNA >2000 IU/mL)
Specific guidelines from AAP or AASLD should be consulted.
Antiviral Agents:
First-line agents include nucleoside/nucleotide analogues such as entecavir (ETV) and tenofovir disoproxil fumarate (TDF) or tenofovir alafenamide (TAF)
Interferon-alfa is an older option, rarely used in pediatrics due to side effects and lower efficacy compared to NUCs.
Pediatric Dosing Considerations:
Dosages for antiviral agents must be carefully calculated based on weight and age, with specific formulations available for pediatric use (e.g., oral solutions)
Regular monitoring for adherence and potential side effects is critical.
Monitoring And Follow Up:
Children with chronic HBV infection require regular follow-up with a pediatric hepatologist or infectious disease specialist
Monitoring includes serial HBV serologies, HBV DNA levels, liver function tests, and imaging studies to assess disease progression and treatment response
Annual screening for hepatocellular carcinoma is recommended for those with cirrhosis or other risk factors.
Prevention And Vaccination
Hepatitis B Vaccination:
Universal HBV vaccination is highly effective and recommended for all infants at birth, followed by a complete series
Catch-up vaccination is crucial for unvaccinated children, including adoptees and immigrants, to prevent infection and reduce transmission.
Hepatitis B Immune Globulin HbIg:
For newborns born to HBsAg-positive mothers, administration of HBIG and the birth dose of the HBV vaccine within 12 hours of birth is essential to prevent perinatal transmission
This protocol should be followed regardless of the mother's nationality or immigration status.
Public Health Measures:
Education campaigns targeting immigrant and adoptee communities about HBV risks, transmission, and the importance of vaccination and screening
Ensuring access to affordable screening and vaccination services for these populations.
Key Points
Exam Focus:
High prevalence of chronic HBV in adoptees/immigrants from endemic regions
Serological markers (HBsAg, anti-HBs, anti-HBc) and HBV DNA interpretation
Indications for antiviral therapy in pediatric chronic HBV
Importance of universal HBV vaccination and post-exposure prophylaxis.
Clinical Pearls:
Always inquire about country of origin for adoptees and immigrants
Remember that chronic HBV can be asymptomatic for years
Early screening and vaccination are paramount
Collaborate with infectious disease specialists or pediatric hepatologists for complex cases.
Common Mistakes:
Assuming all adoptees/immigrants are vaccinated or tested
Delaying screening after arrival
Misinterpreting serological profiles, especially isolated anti-HBc
Inadequate follow-up and monitoring of chronic HBV infection
Failing to administer HBIG and vaccine to infants born to HBsAg-positive mothers.