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transmission rates
Doc, I don't have any STDs and I am trying to keep it that way. I am a probabilities kind of guy. Can you please take your best guestemate at this question... If I had sex with a random person, one time, and that one person did have herpes, what are the chances of it being transmitted. I know it depends on all sorts of stuff, and all incedents are different. But can you give me a ball park figure. IE 1 in 500. Just on avg, whats the chances of transmission per act. Also, if you just absolutely cant answer the question, I might be able to figure it out mathematically. If the avg transmission per year is around 4 % with couples, I could run some combinations and permutations to figure out the chance of transmission per act. However, I would need to know on average how many times these people are having sex that participated in this experiment. 3x, 4x per week??? Do you have any idea on that info as well. The main point of this question though is to see if you could give me a 1 in X guess at the average per act transmission rate assuming the partner is infected, and no valtrex, condom, or antiviral anything involved. Thanks doc.
MEDICAL PROFESSIONAL
Welcome to the STD forum.
Only rough estimates are available. But here are some pertinent data. In a study to determine the effectiveness of antiherpetic therapy (valacylovir) to prevent transmission of HSV-2, monogamous couples who were HSV-2 discordant -- i.e. one with HSV-2, the other without it -- the rate of transmission was about 5% per year. That is, the virus was transmitted in 1 in 20 couples every 12 months. The couples had unprotected sex about 2-3 times per week. For purposes of simple calculation, let's say it was twice a week, i.e. each couple had sex 100 times each year. That means 1 transmission roughly every 2,000 episodes of vaginal sex -- i.e. 0.05% chance for each exposure.
Now let's factor in the odds you have a partner with herpes. That's around 1 in 5 adults in the US, i.e. 20%. That would make your risk of infection, for any single episode of unprotected vaginal sex, something like 0.2 x 0.0005 = 0.0001. That's 1 chance for ever 10,000 sexual exposures.
In the US, HSV-2 rates vary by race (whites and Asians, lower risk, blacks and Latinas higher); and the risk is higher if a partner has newly acquired herpes, perhaps lower if her infection is longstanding. Age is also important, with substantially lower HSV-2 risks in younger women (e.g., under 25) than older. And so on. And most important, much lower if you consistently use condoms.
My advice is to not worry about this too much. And to use condoms for new or casual partnerhips.
Regards-- HHH, MD
Only rough estimates are available. But here are some pertinent data. In a study to determine the effectiveness of antiherpetic therapy (valacylovir) to prevent transmission of HSV-2, monogamous couples who were HSV-2 discordant -- i.e. one with HSV-2, the other without it -- the rate of transmission was about 5% per year. That is, the virus was transmitted in 1 in 20 couples every 12 months. The couples had unprotected sex about 2-3 times per week. For purposes of simple calculation, let's say it was twice a week, i.e. each couple had sex 100 times each year. That means 1 transmission roughly every 2,000 episodes of vaginal sex -- i.e. 0.05% chance for each exposure.
Now let's factor in the odds you have a partner with herpes. That's around 1 in 5 adults in the US, i.e. 20%. That would make your risk of infection, for any single episode of unprotected vaginal sex, something like 0.2 x 0.0005 = 0.0001. That's 1 chance for ever 10,000 sexual exposures.
In the US, HSV-2 rates vary by race (whites and Asians, lower risk, blacks and Latinas higher); and the risk is higher if a partner has newly acquired herpes, perhaps lower if her infection is longstanding. Age is also important, with substantially lower HSV-2 risks in younger women (e.g., under 25) than older. And so on. And most important, much lower if you consistently use condoms.
My advice is to not worry about this too much. And to use condoms for new or casual partnerhips.
Regards-- HHH, MD
excellent answer.
I just can't understand the disconnect between herpes transmission occurring "1 in 10,000 sex acts" to "1 in 4 adults in the US have genital herpes"
I don't know about you guys but I doubt I'm at 10,000 sex acts yet. Although I am working on it.
I just can't understand the disconnect between herpes transmission occurring "1 in 10,000 sex acts" to "1 in 4 adults in the US have genital herpes"
I don't know about you guys but I doubt I'm at 10,000 sex acts yet. Although I am working on it.
good question; great answer.
let's hope everyone uses condoms.
let's hope everyone uses condoms.
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.
