[Question #1344] Hepatitis B

46 months ago
Dr. Handsfield,

On a recent trip to Asia, I regrettably had unprotected heterosexual intercourse with a girl I met. I fully intend to get tested, however in the meantime I was reading up on the low potential risks as a reassurance exercise. I understand (assuming my partner was infected) that the risk for HIV is roughly 1 in 1,000, and for Hep C the risk is near nil.

However what about for Hep B? In a Medhelp post I found you mentioned the risk would only be 1 in 100,000 (http://www.medhelp.org/posts/STDs/hepatitis-b/show/1616164). I just wanted to check I am understanding this correctly? As I think I read somewhere else that Hep B is readily transmitted via sexual intercourse, but 1 in 100,000 would seem to make it a much lower risk than HIV?

Very grateful in advance for all your assistance
Edward W. Hook M.D.
Edward W. Hook M.D.
46 months ago
Welcome to the Forum.  I'll be answering your question today.  FYI, Dr. Handsfield answer questions interchangeably and today I happened to pick up your question.  

There are many variables which impact the risk for acquisition of infection.  Among the are whether or not you have been vaccinated for hepatitis B ( if you were, there is virtually no isk for infection). These include whether or not your partner had infectious hepatitis (unlikely, even in the orient), and the number of acts of unprotected intercourse.  Hepatitis B is thought to be about 10-fold more infections than HIV for exposed, unvaccinated persons but still the risk for any single exposure is low. Taken together, your statistical risk of acquiring hepatitis with any single exposure is quite low.  

I hope this information is helpful.  EWH
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46 months ago
Doctor Hook,

Thankyou very much for your quick response. I should probably mention that the girl in question was a drug user, also that we ended up having unprotected sex more than once (whilst drunk - stupid I know!) And I have never been vaccinated for Hepatitis B.

This only happened a few days ago, so trying to reassure myself and keep calm until enough time has passed to get tested. From your response, it sounds like the risk from Hep B would be as high as 1 in 100 per act, if the girl was infected? Or am I reading this wrong, and in fact the risk is closer to the much lower figure cited by Dr. Handsfield?

Sorry Doctor this is just so I can get an idea of the risk in my mind. For instance I read initially that Hep C was 10x more infectious than HIV, however then found out it is almost never transmitted via heterosexual intercourse, for various reasons.
And then I read Dr Handsfield's medhelp post on Hep B being inefficiently transmitted, and so was hoping this meant it would be less of a risk than HIV. I appreciate the medhelp post is now over 5 years old, and this is obviously a complex topic. Has more information become available in the past 5 years on the risks of transmitting Hep B sexually, or rather was Dr. Handsfield envisaging a specific set of circumstances with the 1 in 100,000 figure?

Thank you so much again for this Doctor
Edward W. Hook M.D.
Edward W. Hook M.D.
46 months ago

Drug user or not, this remains a low risk exposure with a cumulative risk of acquiring hepatitis B as being less than 1 in 1000 and probably far lower.  Dr. Handsfield's reply five years ago reflected risk here in the U.S. and was based on the assumption of a single exposure.  In the orient the risk may be somewhat higher but still quite low, certainly les than 1 in 1000 since you do not know if she was infected or not and statistically, even in the orient, it is unlikely that she had active hepatitis B at the time of your contact.    EWH. 

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46 months ago
Thankyou very much again Dr Hook, this has provided much reassurance. So I am sure I understand this as a layperson (also in case in future I have intercourse with someone I know is infected with Hep B), I have some final questions:

I) Dr Handsfield said in the medhelp post: "heterosexual transmission of HBV is very inefficient; even if your massage partner had HBV and you hadn't used a condom, the odds of transmission from a single unprotected vaginal sex exposure is probably in the range of one in 100,000 or lower."
As a layperson, am I right in thinking this should not be read as the odds when having a single act of intercourse with a known Hep B infected partner are 1 in 100,000 - but rather, the cumulative odds of: the chance of partner carrying Hep B in a developed country x odds of transmission = 1 in 100,000?

II) The odds of catching Hep B from a single act of heterosexual intercourse with a known-infected partner are around 1 in 100? (10x higher than HIV) 

III) "Active Hepatitis B" and "infectious hepatitis" in your answers meaning someone who is currently carrying the virus? Am I correct in thinking most people who do carry the virus would be infectious? (however most people will not be carrying Hep B)

IV) Therefore my odds from my encounter in Asia (per act) would effectively be: 1 in 100 x chance of partner having Hep B = likely greater than in 1 in 1000?

Thank you very much again Doctor

46 months ago
Hi Doctor, sorry just checking if you saw my last questions? Thank you again
Edward W. Hook M.D.
Edward W. Hook M.D.
46 months ago

Sorry I did not reply earlier.  I found your earlier question redundant and did not want to provide a repetitive third and final response to your question.   I will repeat what was said above.  Based on limited studied, hepatitis B is considered about 10-fold more infectious than HIV.  Current estimates are that an uninfected person who has genital sexual intercourse with an infected sex partner has, on average, a 1 in 1000-2000 chance of acquiring infection.  Thus by extrapolation, the risk if acquiring hepatitis b, if one has not had the infection before and is not vaccinated and has a sex partner with active hepatitis B is about 1 in 100-200.  Thus, as you suggested, your risk of acquiring hepatitis be through an unprotected sexual encounter is LESS than 1 in 100 X the chance that a partner has active hepatitis B (most people who acquire hepatitis B get over it and are both immune and non-infectious going forward).  In most setting including ASIA, this translates to a less than 1 in 1000 and typically substantially lower risk of hepatitis B acquisition (i.e. less than 1/10th of 1%). 

I hope this is helpful to you.  As per Forum Guidelines this 3rd response will be my final response as part of this thread and the thread will be closed later today.  If I were you I would not worry too much about having acquired hepatitis B from the encounter you have described.  If you plan future encounters of this sort and are concerned, I suggest you get the hepatitis B vaccine- it is highly effective and would effectively eliminate any risk for hepatitis B you might have.  EWH

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