Doctor to patient transmission of hepatitis B virus: implications of HBV DNA levels and potential new solutions.

Hepatitis B virus (HBV)-infected health care workers (HCWs) can infect patients undergoing exposure prone procedures. Until now reviews have focused on the problem of the HBeAg-positive HCWs. After transmission of HBV by HBeAg-negative surgeons, the focus of Public Health Policy in the UK and the Netherlands has changed from HBeAg status to serum HBV DNA level. Viral load and the volume of blood transmitted determine the transmission risk of HBV. We have estimated the number of infectious particles transmitted by needlesticks, in comparison with those attributed in maternal-fetal transfusion. The blood volume transmitted by needlestick is roughly 1-30% of that of delivery. As vertical transmission with maternal HBV DNA levels below 10(7) g Eq./ml is rarely documented, HBV transmission by needlesticks is, according to our assumptions, unlikely to occur with HBV DNA levels below 10(7) g Eq./ml. Sera of transmitting HCWs contained HBV DNA levels between 5.0 x 10(9) and 6.35 x 10(4) g Eq./ml. Interpretation of these levels is hampered as the sera were taken at least 3 months after transmission. To prevent both loss of expertise and nosocomial infection, highly viremic HCWs can be offered antiviral therapy. Lamivudine and alpha-interferon can now be complemented with adefovir, tenofovir and entecavir to provide effective new therapies for chronic HBV-infected HCWs.