Perinatal transmission of hepatitis B virus: an Australian experience.
OBJECTIVE
To determine the rate of perinatal hepatitis B virus (HBV) transmission in an Australian setting and to identify maternal virological factors associated with highest risk of transmission.


METHODS
A prospective, observational study of perinatal transmission of HBV. Participants were pregnant women attending Sydney South West Area Health Service antenatal clinics who tested positive for hepatitis B surface antigen (HBsAg), and their babies. All babies were routinely offered hepatitis B immunoglobulin (HBIG) and HBV vaccination. Babies positive for HBsAg at 9-month follow-up underwent further virological testing, including HBV DNA sequencing. The study was conducted between August 2002 and May 2008.


METHODS
HBV DNA levels and demographic characteristics of HBsAg-positive pregnant women; proportion of their infants with active HBV infection at 9-month follow-up; maternal characteristics affecting transmission rate; HBV DNA sequencing of infected infants and their mothers.


RESULTS
Of 313 HBsAg-positive pregnant women, 213 (68%) were HBV DNA-positive and 92 (29%) were positive for hepatitis B "e" antigen (HBeAg); 138 babies born to HBV DNA-positive mothers were tested for HBV infection (HBsAg positivity) at about 9 months of age. Four cases of transmission were identified. All four mothers had very high HBV DNA levels (> 10(8) copies/mL) and were HBeAg-positive. Three of the four infants were infected with wild-type HBV strains, with identical maternal/infant isolates. The fourth mother-infant pair had an S gene variant, HBV D144E, which has been previously reported in association with vaccine/HBIG escape. (Unfortunately, HBIG was inadvertently omitted from the immunisation schedule of this infant.) Transmission rates were 4/138 (3%) from HBV DNA-positive mothers overall, 4/61 (7%) from HBeAg-positive mothers, and 4/47 (9%) from mothers with very high HBV DNA levels. No transmission was seen in 91 babies of mothers with HBV DNA levels < 10(8) copies/mL.


CONCLUSIONS
In this cohort, HBV perinatal transmission was restricted to HBeAg-positive mothers with very high viral loads.
Liverpool Hospital, Sydney South West Area Health Service, Sydney, NSW, Australia.
Elke
E
Wiseman
Melissa A
MA
Fraser
Sally
S
Holden
Anne
A
Glass
Bronwynne L
BL
Kidson
Leon G
LG
Heron
Michael W
MW
Maley
Anna
A
Ayres
Stephen A
SA
Locarnini
Miriam T
MT
Levy
D000328:Adult; D001315:Australia / Q000453:epidemiology; D004279:DNA, Viral / Q000097:blood; D005260:Female; D006509:Hepatitis B / Q000097:blood / Q000453:epidemiology / Q000635:transmission*; D006514:Hepatitis B Surface Antigens / Q000097:blood; D006513:Hepatitis B e Antigens / Q000097:blood; D006515:Hepatitis B virus / Q000235:genetics; D006801:Humans; D007231:Infant, Newborn; D018445:Infectious Disease Transmission, Vertical / Q000706:statistics & numerical data*; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000097:blood / Q000453:epidemiology*; D019562:Viral Load
D004279:DNA, Viral; D006514:Hepatitis B Surface Antigens; D006513:Hepatitis B e Antigens