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Transmission probabilities
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Transmission probabilities

Dear Doc,

I am a white male in my mid 30s. The number of sexual partners I have had in my lifetime can be counted using one hand. I now have had genital herpes for about 18 months.I acquired it from my last girlfriend of 5 years -.which had cheated on me and had herself recently infected via unprotected sex. (We know that these were recent infections via the combined Igm and Igg tests) .At the time of infection I use to have unprotected sex with my gf roughly 2 to 4 times a month.  Because of these events and the lost trust - I am no longer in this relationship. Since I'm dating again but haven't yet had sex  since I was last with my last gf - I would like to ask you a  question that relates to the per partnership yearly transmission probability of herpes between a monogamous couple where one is infected and the other is not.  

This question is a follow-up to your answer given in "Question about transmission risk and probability by cantstopworrying". There you state that "...in monogamous couples in which one person has herpes and the other doesn't, and who have unprotected sex 2-3 times a week, only 3-5% of susceptible partners gets HSV-2 per year.  So the chance of herpes from any particular exposure (even if your partner is infected) is very low. "

1) this seems to be very low. - why is it thus said that herpes is very transmissible? I have read this on my other websites.

2) My personal experience suggest a much higher transmissibility (i.e., infectivity). So if the range you quote is accurate -  it seems I have been quite unlucky in catching herpes infection so soon.  I understand that in the case of HIV - a newly infected goes through a primary infection stage of short duration where one is extremely infectious.   I guess this is the case for herpes as well and would explain why I so easily got it - i.e., if my gf was experiencing her initial outbreak when I got infected.
Very roughly - how much more transmissible is herpes during the first initial outbreak?

Note: I'm beyond that - but I think this is very valuable info for the rest of the readers here. Plus this might help explain why herpes is so prevalent. Because with just a  transmissibility of 3-5% yearly chance per partnership  - I find it hard to believe that we have reached the situation where 1 in 4 Americans have genital herpes.

3) I understand that 3-5% is an average. But transmissibility from males to females is greater than females to males.  So is it the case that males to females is more like 5 or 6 % and females to males is like 2 to 3%?  

4) I'm on Valtrex. I have read that this cuts transmissibility by 50%. Thus if on Valtrex a male to female transmission in monogamous relationship, and who have unprotected sex 2-3 times a week the average chances are now roughly 3% of female susceptible partners gets HSV-2 per year. Is this correct?

5) Roughly how much can transmissbilitity be reduced if one practices protected sex 100% of the times and only practices unprotected sex when there are no visible out breaks and using valtex for the purpose of procreation?

6) is there any form of pre-exposure prophylaxis for herpes? If an uninfected person takes valtrex would that decrease the chances of catching herpes when having sex with an infected person?

7) if one uses topical antiviral medications - I would guess that it would further reduce transmission - particularly if applied a little before having sex. Is this correct?

8) Are there any other important ways that one can reduce chances of transmission?

I have many more questions for you that do not relate to transmissibility and I thus think it best if I were to post these in a set of separate questions.

Disclosure: I have worked as a statistician on infectious diseases. How ironic - although I had all the info and I think I was (and still am) careful and generally consider myself to be on the lower risk - some how herpes found a way to reach me. Where I come form there is a saying that goes  "to trust is good but not to trust is better". Boy is that true.

Thank you for your help.
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101028_tn?1348750963
this is not the doctor's forum. You have to pay to post there.

the herpes igm test is a greatly flawed test and we never recommend its use for diagnosing herpes.   Can you call and get your test results to post here for me to look at so we can see if you need additional testing done or not? also did you ever have a lesion culture of active symptoms done?

when a person newly acquires genital herpes, they are more infectious than they are after the first year.  Your gf was actively shedding the virus and transmitted it to you. She didn't know she was infected and you took no precautions at all which is why you so easily became infected ( we'll assume that all your testing was right and she did recently acquire the virus before she infected you ). Studies show that just knowing you are infected with genital herpes, reduces transmission to a partner. don't know you have it, you are likely to have sex when you have obvious symptoms that you would never attribute to herpes.

The risk of transmission from a hsv2+ male to a hsv2- female is on average 8-10%/year if you do nothing but avoid sex any time the male has any obvious genital symptoms. If he also takes daily suppressive therapy with valtrex and the couple uses condoms properly too, the risk is cut to 2-3% each year of transmitting hsv2 to the female. Fairly low rates of transmission with very little effort. The stat you listed in your post is from I assume HHH and it applies to the risk of transmission in general in a couple in which one partner has hsv2.  

No, the uninfected partner taking herpes antivirals does not decrease the risk of them contracting herpes.

The herpes handbook is a free resource for terrific info on herpes - www.westoverheights.com. if you are a more detail oriented person, Terri Warren's book "the good news about the bad news" goes into much more detail and is under $15 on amazon. She is our herpes expert here on medhelp.

grace



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101028_tn?1348750963
this is not the doctor's forum. You have to pay to post there.

the herpes igm test is a greatly flawed test and we never recommend its use for diagnosing herpes.   Can you call and get your test results to post here for me to look at so we can see if you need additional testing done or not? also did you ever have a lesion culture of active symptoms done?

when a person newly acquires genital herpes, they are more infectious than they are after the first year.  Your gf was actively shedding the virus and transmitted it to you. She didn't know she was infected and you took no precautions at all which is why you so easily became infected ( we'll assume that all your testing was right and she did recently acquire the virus before she infected you ). Studies show that just knowing you are infected with genital herpes, reduces transmission to a partner. don't know you have it, you are likely to have sex when you have obvious symptoms that you would never attribute to herpes.

The risk of transmission from a hsv2+ male to a hsv2- female is on average 8-10%/year if you do nothing but avoid sex any time the male has any obvious genital symptoms. If he also takes daily suppressive therapy with valtrex and the couple uses condoms properly too, the risk is cut to 2-3% each year of transmitting hsv2 to the female. Fairly low rates of transmission with very little effort. The stat you listed in your post is from I assume HHH and it applies to the risk of transmission in general in a couple in which one partner has hsv2.  

No, the uninfected partner taking herpes antivirals does not decrease the risk of them contracting herpes.

The herpes handbook is a free resource for terrific info on herpes - www.westoverheights.com. if you are a more detail oriented person, Terri Warren's book "the good news about the bad news" goes into much more detail and is under $15 on amazon. She is our herpes expert here on medhelp.

grace



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Avatar_m_tn
Grace,

Thank you for your answer.

To answer your questions:
I have never done a lesion culture of active symptoms done. I recently went to my doctor and requested it. He said it is a painful procedure and I thus backed off. I have now had my blood test retaken - so I'm waiting to see what is my new Igg count. However - here are the past ones:

April 2010 : Igg count 1.40
July 2010 : took Igg test in a private clinic in my home country. Result was below threshold. I'm not sure what threshold they used and what was the count.
August 2010 (back in the US): Igg count 1.51

All my Igm tests where negative.

Although these Igg counts are quit low positives (from what I understand) - I know I have hsv2 as I recall the first ob in Nov 2009. At the time I didn't know what this was. I went to my doc and he didn't realize either and prescribed a topical cream. Then reading about the prevalence of chlamydia - I went back in April 2010 for the complete set of stds. Hence the test results.

Since my gf at the time admitted that she cheated on me several times with this one guy and had unprotected sex - during the summer of 2009 and since I hadn't been with any other girl since my last std tests (or for that matter since 2003) and also since her test to hsv2 turned out to be positive.... I think I can safely guess  the sequence of events and how I got herpes.

What amazes me is that
1) herpes was not immediately recognized by my doc when I showed him my first ob. -  he didn't even make the recommendation of taking an std test.
2) my gf of the time was regularly taking std test - but those didn't include herpes. Why is this so - with such a prevalent disease?

I know that health-wise - herpes is not a big deal. But it makes you more vulnerable in acquiring other stds. So why not include a herpes test as standard in all std test???

Plus I read that there is a lot of stigma associated with herpes even though health-wise it doesn't seem to be a big deal.

  



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Avatar_f_tn
What test did your ex gf take that was positive?   If it was an IgG, do you have any idea what her numerical values were?

Your two IgG test results are both low positives, as you know.  I urge you to get confirmatory testing with a Biokit or Western Blot.  Your initial outbreak may not have been HSV.  There's no way of knowing since it wasn't cultured.

You said your last std tests before the ones in 2009 were negative -- when was this & are you sure that you had an IgG test done for HSV at that time?  As you know, std tests do not typically include HSV.  Why is that, you ask?  One reason may be that doctors do not want to deal with false positives (a large percentage of positives under 3.5 are false).  Culture/PCR swabs of symptoms are much more accurate.  
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101028_tn?1348750963
preaching to the choir about why herpes testing isn't included in routine std testing!!  More people have herpes than have hiv but we don't test routinely for it. Makes no sense to me especially since we now know that controlling hsv2 helps to reduce infection with hiv.

you certainly need to confirm your infection at this point. Either through a lesion culture of active symptoms ( it's not any more painful than the ob itself ) or through a herpes western blot ( WB ).  No more regular igg blood tests, get the confirmatory testing at this point just to err on the side of caution.  
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Avatar_m_tn
Thanks for the info,

Just got my new IGG test values today - its up to 2.53

Yes - my ex gf had been tested with IGG index. This was early last summer and it was - I think 1.9 ish - if I recall well. But definitely IGG.

All my STD tests did include herpes both IGM and IGG test. So I know I was negative before the fall of 2009. The problem is that when my ex-gf was regularly tested - we found out that her doctor never tested for herpes. She had to specifically requested it once we knew I was positive. That is why I'm also a little more sure about the sequence of events.

If her doctor did test her for herpes - maybe she would have been aware in time before infecting me. She is not a bad person at all. I think she would have told me if she knew. However the cheating by unprotected sex plus this infection has made me too disappointed with what happened.  Now I'm more vulnerable to HIV - and I want to be very safe. The trust has been lost and thus I had to stop our relationship.

Anyway - I'm quite sure I have herpes. I see redness and sores after each ob. I have all the described symptoms - itchiness and tingling etc.  The ob don't look very bad but I can recognize the marked similarity with those shown in internet photos( the ones showing mild ob - thankfully not the worst case scenario ones).

Question:  I spoke with my doc about my igg having increased to 2.53 - I asked what does this mean. He tells me that it means nothing - it just indicates that I have been exposed. I asked him - doesn't this mean my antibodies are more prepared to fight off the occurrence of ob? He said no. I'm thus very confused on what the level of IGG indicates and why is 0.9 to 1.1 IGG chosen as threshold level? Can someone have IGG levels of say a constant value of 0.8 over many years? - this person would  thus be negative. But how would he get to a level of 0.8? I don't quite get it. Any clarification on this?





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101028_tn?1348750963
you both have low positives that need confirmed with additional testing.  

there is no such thing as being exposed - you are either infected or you aren't.  The numeric value is rather meaningless other than if you are positive, negative or in the range that requires additional confirmation of status due to the well known false positive issues.  

you never get a 0 as a test result due to the way they do the test. they compare your sample to a control sample and what you get is actually a percentage of likelihood you are infected that is converted into a numeric result.  results under 3.5 have a decent chance of being falsely positive which is why additional testing is recommended unless you have a + lesion culture to confirm your status.  
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Avatar_m_tn
Thank you Grace for all the answers and suggestions. I'll insist with my doctor to get further tests when I next see him.

I would like to return to the topic of transmission rate in your answer you gave:

"The risk of transmission from a hsv2+ male to a hsv2- female is on average 8-10%/year if you do nothing but avoid sex any time the male has any obvious genital symptoms. If he also takes daily suppressive therapy with valtrex and the couple uses condoms properly too, the risk is cut to 2-3% each year of transmitting hsv2 to the female. Fairly low rates of transmission with very little effort. The stat you listed in your post is from I assume HHH and it applies to the risk of transmission in general in a couple in which one partner has hsv2.   "

are these probabilities  based on having sex on average 2 -3 times a week? as given in the answer "Question about transmission risk and probability by cantstopworrying".

This could then help me understand what is the probability per act rather than per partnership.

Thanks.
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101028_tn?1348750963
yes and no. the valtrex and reduction in transmission study had an average of sex twice a week in it but the stats are also confirmed by other studies in the past that looked at rates of transmission too.


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