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acyclovir and transmission probabilities
My partner of the past 6 weeks has herpes simplex 2. I have used protection except for a few times (she was asymptomatic). I have not had symptoms. I plan to test after 12-16 weeks with no more unprotected sex before then. She has no insurance and Valtrex is too expensive. I have read/heard quite different accounts about the extent to which the less-expensive acyclovir provides protection to potential partners: I understand it reduces the frequency of outbreaks and of asymptomatic shedding to some degree. I have had cold sores (i.e., HSV-1) as long as I remember (certainly before sexual activity), and I understand this also provides some protection. Assume I am uninfected. Suppose she starts using daily suppressive treatment with acyclovir, and we did not have unprotected sex during symptomatic outbreaks. What does best science suggest the probability of me becoming infected would be per year, if there were,say, 50-60 varginal exposures per year without using condoms (I'm just expecting your best sense on this)? What should the daily dosage regime be? How much would condom use lower the risk? Finally, since I have HSV1 already, what could you say about the risks to me of giving her oral sex?
MEDICAL PROFESSIONAL
The risk of HSV-2 transmission depends on many factors, some of which are not known (often cannot be known) in individual couples. For example, some persons not having symptomatic herpes outbreaks have more asymptomatic viral shedding, when transmission can occur, than others. How long your partner has been infected also makes a difference; if she is within the first few months of catching genital HSV-2, the risk is much higher than later -- and if it has been several years, the risk might be quite low.
As for your own HSV status, there is some possibility you already have HSV-2 yourself, since 20% of all adults (in the US) have positive blood tests. That is the main reason you should have HSV blood test, to know about HSV-2; your HSV-1 status probably makes no significant difference. But if you are "lucky" enough to already have HSV-2, you won't catch it again and will have no worries of getting infected again. There are conflicting research data on whether HSV-1 protects against HSV-2. If it does, the effect is small and it's not something that can be relied on over a long term relationship.
Consistent use of condoms is highly effective, but not perfect; over time, the risk is probably reduced by around 80%.
Acyclovir might be just as effective as valacyclovir (Valtrex) in reducing transmission risk; it simply has not been evaluated in research studies. It reduces asymptomatic viral shedding as well as valacylovir, so prevention of transmission probably is about the same. The usual dose is 400 mg twice daily.
Putting these factos together, to answer your closing questions: If you follow all 3 strategies (avoid sex during your partner's outbreaks, acyclovir treatment, plus condoms), the risk of transmission would be very low; you might go a lifetime with regular sex without ever catching HSV-2. Take away any one of them and the risk rises. Still, dropping condoms from the mix, most likely your 50-60 episodes of vaginal sex per year would not result in transmission. But of course the risk would rise over time, so someday transmission might occur. However, there are no numerical data to give a more detailed response than this.
Asymptomatic viral shedding in the mouth is less common in people with oral HSV-1 than for genital HSV-2. Most oral to genital HSV-1 transmission probably occurs during overt herpes outbreaks (cold sores). While it is possible she could acquire a gential HSV-1 infection on top of her genital HSV-2, that appears to be a rare occurrence. I wouldn't worry about it.
Finally, you and your partner need to make a decision about how much hassle you are willing to endure to prevent transmission. If your relationship evolves into a committed, permantent one, you might decide to just let nature take its course; if transmission occurs, effective treatment is available -- and in that cirumcstance, there presumably would be no concern about transmitting herpes to yet another person. Since research shows that transmission is infected persons' greatest single fear, perhaps this would be a reasonable attitude by you and your partner.
Congratulations on a level headed attitude toward genital herpes. Consider visiting the MedHelp herpes community forum for more detailed discussion with excellent advice by the excellent forum moderators, who are experience herpes clinicians and counselors.
Best wishes-- HHH, MD
As for your own HSV status, there is some possibility you already have HSV-2 yourself, since 20% of all adults (in the US) have positive blood tests. That is the main reason you should have HSV blood test, to know about HSV-2; your HSV-1 status probably makes no significant difference. But if you are "lucky" enough to already have HSV-2, you won't catch it again and will have no worries of getting infected again. There are conflicting research data on whether HSV-1 protects against HSV-2. If it does, the effect is small and it's not something that can be relied on over a long term relationship.
Consistent use of condoms is highly effective, but not perfect; over time, the risk is probably reduced by around 80%.
Acyclovir might be just as effective as valacyclovir (Valtrex) in reducing transmission risk; it simply has not been evaluated in research studies. It reduces asymptomatic viral shedding as well as valacylovir, so prevention of transmission probably is about the same. The usual dose is 400 mg twice daily.
Putting these factos together, to answer your closing questions: If you follow all 3 strategies (avoid sex during your partner's outbreaks, acyclovir treatment, plus condoms), the risk of transmission would be very low; you might go a lifetime with regular sex without ever catching HSV-2. Take away any one of them and the risk rises. Still, dropping condoms from the mix, most likely your 50-60 episodes of vaginal sex per year would not result in transmission. But of course the risk would rise over time, so someday transmission might occur. However, there are no numerical data to give a more detailed response than this.
Asymptomatic viral shedding in the mouth is less common in people with oral HSV-1 than for genital HSV-2. Most oral to genital HSV-1 transmission probably occurs during overt herpes outbreaks (cold sores). While it is possible she could acquire a gential HSV-1 infection on top of her genital HSV-2, that appears to be a rare occurrence. I wouldn't worry about it.
Finally, you and your partner need to make a decision about how much hassle you are willing to endure to prevent transmission. If your relationship evolves into a committed, permantent one, you might decide to just let nature take its course; if transmission occurs, effective treatment is available -- and in that cirumcstance, there presumably would be no concern about transmitting herpes to yet another person. Since research shows that transmission is infected persons' greatest single fear, perhaps this would be a reasonable attitude by you and your partner.
Congratulations on a level headed attitude toward genital herpes. Consider visiting the MedHelp herpes community forum for more detailed discussion with excellent advice by the excellent forum moderators, who are experience herpes clinicians and counselors.
Best wishes-- HHH, MD
MEDICAL PROFESSIONAL
There are no data, but probably zero risk or close to it. Oral herpes due to HSV-2 is rare.
Thanks Doc!!
This forum is invaluable to many! Keep up the great work!
This forum is invaluable to many! Keep up the great work!
Thanks for a great, patient, informative reply! What is the risk TO ME of giving oral sex to her (with her on acyclovir)?
You are reading content posted in the STDs Forum
Herpes spreads by oral, vaginal and anal sex.
Herpes sores blister, then burst, scab and heal.
STIs are the most common cause of genital sores.
Millions of people are diagnosed with STDs in the U.S. each year.
STDs can't be transmitted by casual contact, like hugging or touching.
Syphilis is an STD that is transmitted by oral, genital and anal sex.
