[Question #1539] Hepatitis B Transmission

83 months ago
Hello Dr. Hook,

First of all thankyou for your last answers to my question sometime ago, where you very helpfully explained that the chance of contracting Hepatitis B from a heterosexual encounter with someone who was infected, would be roughly 1 in 100.

I read sometime ago Dr Handsfield say on another Medhelp post that the "risk of hepatitis B from any particular episode of heterosexual exposure is extremely low" and there was a "low chance" of infection even if the person had hepatitis, in this post: http://www.medhelp.org/posts/STDs/Question-about-Hepatitis-B-testing/show/615638 . 

So I wanted to ensure I understand as layman, is the reason the risk as stated by Dr Handsfield is so low, because not many people will have hepatitis B infection in a western country? As my understanding from our last answer here was the risk would be 1 in 100 from a heterosexual encounter (with an infected person) which seems high - but Dr. Handsfield's post seems to indicate the risk would be extremely low?

Was 1 in 100 the result of new research showing greater risks of hepatitis B from heterosexual sex, or did Dr. Handsfield's response mean extremely low in the context of few people in the western world having hepatitis, i.e. 1 in 100 infection risk x 1 in 1000+ of a person having hepatitis B?

Thankyou again Dr for your most kind assistance

H. Hunter Handsfield, MD
83 months ago
Welcome back to the forum. I'll be answering your question this time. I reviewed your earlier discussion with Dr. Hook.

You are very focused on the particulars of sexual transmission risk for HBV. The problem is that data simply do not exist to allow the risk esimates you seek. What we do know is that although on a worldwide scale, heterosexual transmission accounts for a lot of hepatitis B, it is a very rare outcome after any single exposure. Any esimtates of actual numerical risk however, are pretty much wild guesses:  this has never been researched. I can't say how I came up with the 1 in 100,000 risk that you quote from a distant past reply to a question on a different forum -- I would have to see the specific question to which I was responding. But what does it matter if the true risk is, say, one in a thousand versus 10,000 versus 100,000? It's low enough tnat no STD experts ever recommend testing after any single exposure, except maybe in particularly high risk situations, such as a traumatic (bloody) sexual event with a known infected person. 

In any case, why keep worrying and speculating when the answer as to whether you migth have been infected is immediately available? Your last question was posted about a month ago, and the exposure was sometime "recently" before that. So presumaby it was at least 5-6 weeks ago, right? If so, just get tested. You can expect a negative result, which will be more reassuring than anything we can say. With the expected negative result, then speak with your physician about starting HBV immunization.

I hope this has been helpful. Let me know if anything isn't clear. Best wishes--  HHH, MD

83 months ago
Thankyou Dr. Handsfield for your very prompt response, it is most appreciated.

I should probably have added that the reason I am asking is that unfortunately I did not learn from my mistakes, and very recently (last week) had an unprotected heterosexual encounter, with someone who is a known drug user. I also have other reason to believe she is currently infected with Hep B.

I realise that she may not be currently infected with Hepatitis B for certain. But assuming she is infected, is there zero data available to give an approximate risk - Dr Hook mentioned that there were published research studies (although limited) which all suggested the risk was 1 in 100, i.e. roughly 10x higher than HIV? 

When you say the risk is low enough that no experts recommend testing after a single exposure, is that a single exposure with a person of unknown status?

Understand there is a limited data on this subject, however  I am trying to get an idea of my risks compared to other STDs, e.g. I think HIV is widely stated as 1 in 1000 - 1 in 2000 (per encounter).
So given I cannot yet get tested, would it be possible to at least say if the risk (from a single heterosexual encounter) of Hep B with a known infected person is likely similar to HIV risk, or higher/lower - i.e. would it likely be closer to the 1 in 100 mentioned by Dr Hook, or in fact lower risk than HIV, e.g. closer to 1 in 10,000?

Very many thanks again Dr

H. Hunter Handsfield, MD
83 months ago
Sigh. I've given the reasons why a numerical estimate is not possible. On top of all I said, the status of the HBV infection in your partner, if she were infected, is crucial but unknowable. Most people infected with HBV clear their infections entirely and are not infectious at all. Others, chronically infected, have very little virus in their blood and are minimally infectious if at all. (Probably I was thinking of such persons with my 1 in 100,000 estimate a few years ago.) At the other end of the scale, if someone had a new infection and was about to blossum with overt hepatitis, the transmission risk would be very high. But in general, only a small minority are capable of transmitting at all. So most likely you had zero risk of catching it. But f you want to continue to insist on a numercal, I'll go along with your closing statement, i.e. "closer to 1 in 10,000".

My main advice remains the same. Putting aside other risks (STDs, HIV) and thinking only of HBV, which for some reason seems to be your laser focus:  Do not get tested. Continue sex with your regular partner. If you feel you simply must be tested, do that at 6 weeks after the event. And for goodness' sake, get vaccinated!

Finally, what's wrong with condoms?

83 months ago
Thanks Dr, yes you are very right I should always have used condoms.

That makes sense everything you have told me. I would lastly enquire, if the risk of single encounters is low (i.e. closer to 1 in 10,000), how do people living with Hep B-infected partners end up catching the disease much more regularly? Like I read here in a large study that people living with Hep B partners are much more likely to become infected - http://www.ncbi.nlm.nih.gov/pubmed/18313290 . 

I guess, question is how does this happen? If odds are as high as 1 in 10,000, couples could have unprotected sex for many years without ever being infected? I know there could be also be risk from shared razors and other personal items, but I understand from reading online this risk is very low (lower than sexual exposure in fact?) So just wondering how then in studies and on CDC site, household partners are at more risk?

I ask this as I have also before lived for 3 months with a drug-using partner (you probably seeing a pattern here). We always had protected sex, and I myself am not a user so there was no sharing of drug equipment. But am I missing something here - why are household partners stated to be at much greater risk when the odds from both heterosexual encounters and sharing razors / hygiene items is so low?

Due to upcoming holidays I cannot immediately go get tested. So any expertise you can provide here would help greatly. Yes I admit am focused on Hep B, mainly because of lack of info online - the risks for HIV and Hep C seem to be well-quantified (as being very low) so less of a concern.

Thankyou once more Dr
83 months ago
And sorryDr, just so I fully understand as lay-person - when you say the risk from an acute/new Hep B infection would be very high, would this likely be much closer to the 1 in 100 risk Dr Hook was referring to? This is what I think you mean but want to be sure.

Thankyou again
H. Hunter Handsfield, MD
83 months ago
What does it matter what words are used to describe the level of risk? At a population level -- what a public health department should be worried about -- 1 chance in 100 definitely is high risk. But for any single person, it means an unlikely chance of transmission for any single exposure, so that person may consider the risk low.

As discussed above, not all infected people with past or current HBV are infectious for their partners, either sexual or household. An average risk of one if a few thousand includes some couples with nearly 100% chance of transmission to the uninfected partner within a year, and in others with zero risk.

Finally, you're a household contact of a drug using partner? So what is his or her HBV status? And why in heaven's name haven't you been vaccinated, instead of spending so much mental energy worrying about a risk that may or may not exist???

Repeated anxiety driven questions are against forum policy, as I think you know. This is your last question about HBV and its risks. Any additonal ones will be deleted without reply and without refund of the posting fee.