Infections in pregnancy – hepatitis B (HBV)

DEFINITION “hepatitis B” refers to inflammation of the liver caused by the hepatitis B virus.

AETIOLOGY: Acquired by sexual contact, blood-borne and vertical transmission.

RISK FACTORS

    o   Multiple sexual partners,  

    o   unprotected sexual intercourse, 

    o   intravenous drug use,

o

EPIDEMIOLOGY Affects 1 per 100 000 pregnancies.

SYMPTOMS:  Asymptomatic in70%. Fever, myalgia, nausea, vomiting, jaundice, abdominal pain.

SIGN: Jaundice, hepatomegaly, right upper quadrant tenderness.

  CAUSATIVE AGENT:

Double-stranded DNA virus (Hepadanavirus family) The hepatitis B virus contains an outer envelope composed of a surface protein called the hepatitis B surface antigen or "HBsAg". The HBsAg can be detected by a simple blood test and an inner core a protein shell referred to as the hepatitis B core antigen or "HBcAg," which contains the hepatitis B virus DNA and enzymes used in viral replication.

INCUBATION PERIOD: 2–6 months.

INVESTIGATIONS

Blood: HBsAg (infection), core antibody (anti-HBc IgM – acute infection), hepatitis B e-markers (HBeAg – high infectivity), LFTs.

PREVENTION: Pregnant women at risk for HBV infection should receive hepatitis B vaccination.

Pregnancy is not a contraindication to vaccination.

     For vaccination of adults 20 years of age and older: 1-mL dose by intramuscular injection into the deltoid muscle, at initial visit, then second and third doses after a month and six months after the first dose, for a total of three doses.       

 

MANAGEMENT

Delivery:

Avoid FBS/FSE. Delivery by cesarean section for the purpose of reducing MCT of HBV is not presently recommended by either the CDC or the ACOG.

Postnatal:

Mothers can breastfeed. The second dose of vaccine should be given at age 1–2 months, and the third dose at age 6 months. The infant should be tested after completion of the vaccine series, at age 9–12 months (generally at the next well-child visit), to determine if the vaccine worked and that the infant is not infected with HBV through exposure to the mother’s blood during the birth process. However, there is no need to delay breastfeeding until the infant is fully immunized. The risk of HBV mother-to-child transmission through breastfeeding is negligible if infants born to HBV-positive mothers receive the HBIG/HBV vaccine at birthWith appropriate hepatitis B immunoprophylaxis, breast-feeding does not appear to pose additional risk for transmission from infected hepatitis B virus carriers to their infants

Neonatal vaccination:

All infants born to HBV-infected mothers should receive hepatitis B immune globulin (HBIG) a must if acute infection occurred in pregnancy/ if e-markers are unknown and for newborn having birthweight <1500 g and the first dose of hepatitis B vaccine within 12 hours of birth at birth, 1 month, 2 months and booster at 1 year.

COMPLICATIONS

Maternal: 10% develop chronic disease (chronic hepatitis, cirrhosis), risk of hepatocellular carcinoma, 1% develop fulminating hepatitis.

Neonates: 90% of babies infected with hepatitis B develop chronic hepatitis.

PROGNOSIS With appropriate treatment, vertical transmission rate is 10%. With chronic HBV infection, the risk of death from cirrhosis or hepatocellular carcinoma is 15%--25%.