Viral and bacterial factors of mother-to-child transmission of hepatitis B virus

Hepatitis B virus (HBV) infection is the tenth leading cause of death worldwide. Mother-to-child transmission of HBV occurring mainly at delivery remains one of the most common routes of infection in developing countries. One of the main challenges concerning HBV in Africa is to implement a prevention policy aiming at interrupting the cycle of pseudo-vertical transmission of this infection. The aim of this study was to assess the implication of certain bacterial and viral factors in mother-to-child transmission of HBV. This prospective study was conducted on 165 pregnant women carriers of HBV surface antigen (HBsAg) and their 169 newborns who attended care at the Gynecology Department of the University Hospital of Cocody. Serological, molecular, and bacteriological analyses were performed on blood samples and vaginal secretions. Mean viral load (VL) was 4.5 +/- 1.3 log(10) IU/ml, while mean HBsAg titres were 3.5 +/- 0.9 log(10) IU/ml. HBV DNA was found in vaginal secretions in 13.3% of mothers and in the blood of 10.3% of the newborns. Six bacterial species were identified in the vaginal discharge of pregnant women during labour before delivery. Staphylococcus aureus and Enterococcus faecalis were the most frequent species found in 23.0% and 13.9% of cases. Mothers positive for vaginal HBV DNA displayed higher plasma HBV DNA loads than negative mothers (6.2 +/- 1.6 log(10) IU/ml vs. 4.3 +/- 1.0 log(10) IU/ml, p < .0001). In conclusion, our study showed that presence of HBV DNA in vaginal secretions and the presence of S. aureus could play a role in mother-to-child transmission of HBV. HBV DNA detection in vaginal discharge represents a promising biomarker to identify newborns at risk of perinatal persistent infection.