Hepatitis B Transmission and Prevention
Hepatitis B virus (HBV) is primarily transmitted through percutaneous exposure to blood, sexual contact, and from mother to child during birth, with vaccination being the most effective prevention strategy. 1, 2
Modes of Transmission
Blood-borne Transmission
- Percutaneous exposure is the most efficient mode of transmission 1:
- Injection drug use (sharing needles/equipment)
- Needlestick injuries in healthcare settings
- Contaminated medical or dental instruments
- Unsafe injections
- Organ transplantation and dialysis
Sexual Transmission
- HBV is efficiently transmitted through sexual contact among both heterosexuals and men who have sex with men (MSM) 1
- Risk factors include:
Perinatal/Vertical Transmission
- Mother-to-child transmission during childbirth is a major route in endemic areas 3
- Transmission risk is 70-90% when mothers are both HBsAg and HBeAg positive 2, 4
- Despite immunoprophylaxis, vertical transmission may still occur in 1-14% of cases 5
Household/Close Contact Transmission
- Sharing personal items with infected individuals (toothbrushes, razors) 1, 2
- Contact with exudates from dermatologic lesions
- Contact with HBsAg-contaminated surfaces
- Common in settings like schools, childcare centers, and facilities for developmentally disabled persons 1
Infectious Body Fluids and Environmental Factors
Highly Infectious Fluids
- Blood contains the highest concentration of HBV 1, 2
- Semen and vaginal secretions are infectious 1
- Saliva can contain detectable virus 1
- Other potentially infectious fluids include cerebrospinal, synovial, pleural, peritoneal, pericardial, and amniotic fluids 1, 2
Low-Risk Fluids
- Urine, feces, vomitus, nasopharyngeal washings, sputum, and sweat are not efficient vehicles unless they contain blood 1, 2
- HBsAg in breast milk is unlikely to lead to transmission; breastfeeding is not contraindicated 1, 2
Environmental Survival
- HBV remains viable on environmental surfaces for at least 7 days 1
- Can be transmitted even without visible blood present 1, 2
- Approximately 100 times more infectious than HIV 2
Prevention Strategies
Vaccination
- Universal vaccination is the cornerstone of prevention 1, 2, 6:
- All infants beginning at birth
- Previously unvaccinated children under 19 years
- Adults at risk for HBV infection
Perinatal Prevention
- Screen all pregnant women for HBsAg 1, 2
- HBV DNA testing for HBsAg-positive pregnant women 1
- Maternal antiviral therapy when HBV DNA is >200,000 IU/mL 1, 5
- Prophylaxis for infants born to HBsAg-positive women:
Other Prevention Measures
- Safe injection practices and blood screening 2
- Safe sex practices and condom use 2
- Avoid sharing personal items with infected individuals 2
- Proper infection control in healthcare settings
High-Risk Populations
- Infants born to infected mothers 4, 3
- Injection drug users 2
- Sexual partners of infected individuals 2
- Men who have sex with men 1
- Healthcare workers with occupational exposure 2
- Household contacts of infected persons 2
Common Pitfalls and Misconceptions
- Not recognizing that all HBsAg-positive individuals are infectious, even without symptoms 1, 2
- Failing to screen pregnant women, which misses opportunities for prevention 1, 4
- Misconception that casual contact can transmit HBV (hugging, sharing food, coughing) 2
- Delaying birth dose of hepatitis B vaccine beyond 24 hours, which reduces effectiveness 1
- Assuming breastfeeding is contraindicated for HBV-positive mothers 1, 2
By implementing comprehensive prevention strategies, particularly universal vaccination and proper perinatal prophylaxis, the global burden of hepatitis B infection can be significantly reduced, ultimately decreasing morbidity and mortality from chronic liver disease and hepatocellular carcinoma.