Mother-to-child transmission of hepatitis B virus (HBV) continues to occur despite immunoprophylaxis.
Dr Singh and colleagues examined maternal factors contributing to transmission in infants receiving adequate immunoprophylaxis in Alberta, Canada.
Prenatal specimens from hepatitis B surface antigen-positive women whose babies developed hepatitis B virus infection despite immunoprophylaxis (cases) and hepatitis B surface antigen-positive mothers whose babies did not (controls) were tested for hepatitis B surface antigen, hepatitis B e antigen and hepatitis B virus DNA.
Specimens with detectable DNA underwent hepatitis B virus genotyping.
|Viral load in the other case was 14 000 IU/mL|
|J Viral Hepatitis|
Routinely collected surveillance data and laboratory test results were compared between cases and controls.
The research team found that 12 cases and 52 controls were selected from a provincial registry from 2000 to 2005.
At the time of prenatal screening, median maternal age was 31 years, and median gestational age was 12 weeks.
Cases were more likely than controls to test positive for hepatitis e antigen.
Of all mothers with detectable viral load, cases had a significantly higher median viral load than did controls.
Of the 2 cases who were hepatitis e surface antigen negative, 1 had an undetectable viral load 8 months prior to delivery and a sP120T mutation.
The research team found that viral load in the other case was 14 000 IU/mL.
The team noted that the majority of isolates were genotype B and C with no significant differences in genotype between cases or controls.
Dr Singh's team concluded, "In this case–control study, transmission of hepatitis B virus to infants was more likely to occur in mothers positive for hepatitis e antigen and with high hepatitis B virus DNA."