[Question #28] STI risk assessment

40 months ago
Dr HHH,  First let me take the time to thank you in advance for answering my question.  

 I am a heterosexual, circumsized  male in my 40s.  On 10/06/14 I had an encounter with a female CSW.  I received brief oral from her.  Prior to doing so , I did not see any visible sores on her mouth.  She was seated on top of my chest facing away from me and I did not observe any visible lesions on her vagina.  The oral lasted for approximately 30 seconds.  Now on to my biggest concern.   I engaged in unprotected intercourse with her.  That consisted of me inserting my penis into her wet feeling vagina.  I then "pumped" one time then withdrew.  The activities were not vigorous and lasted a total of 20 seconds max.

I tested for gonorrhea, chlamydia and and NGU 7 days after the incident.  The results came back 3 days later and all were negative.   During those 10 days, I inspected my penis numerous times each  day.   I never saw anything that even remotely resembled a pimple or blister during that time.  I also have taken tests for HIV, Hepatitis B and C and syphillis, all of which were negative.   

I have gotten a tingle or pinching  sensation on various spots on my penis since then which caused me to inspect it numerous times a day for at least a week or more each time.   I am obviously no doctor,  but I have never observed a lesion or anything else that resembled  one and lasted for a week or more.

Could you please give me an overall risk analysis regarding this incident. I know it may be difficult,  but could you give me statistics regarding likelihood of catching herpes during this encounter?   I am concerned about herpes still to this date,  almost 9 months after the incident.   Do you think I should be tested for herpes,  or was the risk to low?  Again,  thank you for your time and I look forward to your response. 
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
40 months ago
Welcome to the forum. Thanks for your question.

The risk of any STD typically is low for any single exposure, even in the highest risk settings. You had unprotected vaginal sex, by far the highest risk element of the exposure described. The risk was probably even lower than usual given its brevity, but you certainly could have acquired almost any STD. However, it is very unlikely that you did. The gonorrhea and chlamydia tests are conclusive, and you can also be confident you didn't acquire NGU. You don't say the timing of your blood tests, but if done sufficiently long after the exposure -- 3 months would cover all 4 of the infections mentioned -- those results also are conclusive. As for your "tingling" sensation, that's almost certainly psychological, i.e. anxiety over the event magnifying normal body sensations or trivial feelings that you otherwise wouldn't notice. In my 40+ years in the STD business, I've never seen anyone with such symptoms that turned out to have an STD as the cause. Certainly herpes cannot do this.

Should you be tested for herpes? From a strictly medical perspective, I see no need. And if you have a positive result, it would almost certainly reflect an infection entirely unrelated to the exposure above. In any randomly selected mid-40s male in the US, 15-20% will have positive tests for HSV2 and 30-50% for HSV1. So if positive, you'd have to deal with that and its implications. OTOH, if negative, it might allay your continuing anxiety over a sexual decision you apparently regret. Of course there's also the slight possibility of a misleading result, such as a low positive that doesn't even give a clear answer. In other words, it's up to you -- but at a personal level, if somehow i were in your circumstance, I wouldn't do it.

In summary, the chance you have any STD from this exposure is zero for all practical purposes. Do your best to stop worrying about it, and for sure continue or resume regular sex with your main partner, if you have one.

I hope this has helped. Best wishes--  HHH, MD
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40 months ago
Dr. Handsfield, thank for your response.   My tests for the other sti's post exposure were 6,9,12 and 20 weeks, are those conclusive?

A couple more follow up then I will end this thread, I promise. 

 1. I read some of your previous posts from medhelp and you  mentioned on that site that the risk from a single exposure to an hsv infected person is in the area of 1 in 1000 to 1 in 10,0000, would those numbers still be correct today (the last post that I could find on medhelp was dated June of last year)?

2.  I haven't had an outbreak in almost 9 months.  I have read that if a person contracts hsv, they have their initial outbreak then on average,  they have 3 to 6 recurrent outbreaks a year.  Since I haven't had any lesions that I recognized as an initial outbreak and certainly no reoccurring outbreaks, can I interpret that as further proof that I was not infected from this exposure?  
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
40 months ago
You were rather seriously over tested! Those results were conclusive at 12 weeks, nearly so at 6 and 9 weeks.

1) The most precise data on HSV transmission risk is from analysis of the placebo controls in the study showing transmission protection with valacyclovir. In monogamous couples in which one person had HSV2, who had unprotected vaginal sex an average of 2-3 times a week, transmission occurred in 5% of susceptible partners (one in 20) per year. This works out to somewhere around once for every 1,000 exposures. The risk logically is higher or lower depending on individual circumstances. With a partner not known to have herpes, but who might have a 10% chance of having HSV2, that would work out to around once for every 10,000 events. (I don't recall if that's how I came up with a prior estimate in that range. Probably.)

2) Yes, absence of symptoms is additional evidence that you didn't catch herpes.
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40 months ago
Dr. Handsfield,  I want to thank you for taking the time to answer my questions throughly.   Because of you,  I will finally be able to put this behind me.  I have no further questions and you can close this thread at your leisure.   
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
40 months ago
Thanks for the thanks. Glad to have helped.---