[Question #3944] Basis for safe sexual activity

31 months ago

Hello,

 

If I may, I would like some clarification on the following topics:

 

First, it is my understanding that in order to contract an STI, there must be orifice, that is oral, vaginal, or anal sex. If so, is the evidence supporting this statement that sufficient sexual-oriented germs must enter inside the body? That orifice is the incidence where that is possible?

 

Second, it is my understanding that most STI’s are mild and/or with no symptoms. If so, is the evidence supporting this statement that there is orifice and there is sufficient transmission of infected fluid but the immune system doesn’t readily clear it? Conversely, for STI’s that are moderate and above, would incidences where sufficient fluids are transmitted always subsequently cause symptoms within a 2-10 day window? Is there a causal relationship between severity and symptoms? Lastly, is it possible to sufficiently transmit infectious fluid in one encounter? 

Edward W. Hook M.D.
Edward W. Hook M.D.
31 months ago
Welcome to the forum.  Your questions are a little hard for me to follow but I will try to provide information for you regarding sexually transmitted infection transmission.

  There are over 30 different bacteria and viruses which are transmitted through sexual contact. The efficiency with which they are transmitted varies depending on the infection and the mode of transmission.   The most common sexually transmitted infections such as gonorrhea, chlamydia and trichomonas are spread by penetrative sexual contact involving mucous membranes.  Some less common STIs like HIV and hepatitis B are also spread in this fashion. These infections are spread through direct contact  of mucosal surfaces between infected and non-infected persons. 

 Some other STIs such as HPV and much less commonly,  genital herpes or syphilis can be transmitted through direct contact of an infected lesion with non-infected, intact, non-mucosal skin.   In infections of this variety, it is thought that the friction involved with sexual activity may cause micro abrasion's which enhance the chance of transmission. 

 For both of the categories of STI's I mentioned above, transmission is rare. Most sexual contact with infected persons do not lead to transmission.    Even if a sexual partner has an STI, transmission of infection in a single encounter is uncommon occurring only in the minority of circumstances. Further, correct and consistent condom use dramatically reduces the risk of transmission of all STIs.

 As you point out, the majority of all sexually transmitted infections are asymptomatic and when  symptoms occur their intensity can be variable. The frequency which with different STI & HIV cause symptoms varies from infection to infection and with site of infection. When symptoms occur they may well be minor and go unnoticed if  persons are not looking for them. 

 I hope that this information will be helpful to you if there are specific questions about a specific encounter or a specific STI I would be happy to try to clarify them and your up to two allowed follow-up questions. EWH. 
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31 months ago

You mention that transmission is rare even with an infected person. However, if a typical encounter entails both penetrative and frictional (direct) contact, how could transmission be rare if the mechanisms for transmission exist in each encounter? Is there an insufficient amount of any given virus spread in a single encounter typically? Further, in the rare cases when transmitted, would that be due to a weak immune system at that time or perhaps a genetically weak area at the site of infection?

 

While symptoms are specific to particular infections and the site of infections, it is not clear to me if there is a causal relationship between severity or strength of an infection and symptoms. If symptoms do exist, does that mean that the infection is either the appropriate type and/or is located at the appropriate site where it is strong enough to cause symptoms that the immune system cannot readily or at all clear without treatment? Otherwise, I have no indication that there has been transmission and implies that I must be comfortable with the risk of any activity and trust my immune system to clear infections if most infections are asymptomatic and there are no reliable tests to show conclusive results for some infections.

 

Essentially, I would like to avoid the concern or need for testing and be confident in my understanding of how certain sexual activity is safe. If there were a causal relationship between severity of infections on the body and symptoms, no symptoms within a 2-10 day window would suggest that the infection was mild and the immune system had cleared it. Conversely, if there were symptoms by the 10th day, it would suggest a more moderate to possibly severe case and then certain action may be necessary. Am I oversimplifying this? 


Thank you Doctor.

Edward W. Hook M.D.
Edward W. Hook M.D.
31 months ago
You are being a bit argumentative.  The majority of unprotected, single sexual exposures to partners who have STIs do not lead to infection.  This is a FACT. It is well studied for gonorrhea and HIV and estimated for most other STIs (and no, I am not going to make a list for you of estimated transmission efficiency). The risk of gonorrhea transmission in vaginal intercourse when the man is infected and his female partner is not is about 30-40% transmission per unprotected sex act.  For uninfected men having unprotected contact with an infected woman, transmission to the man occurs about 20% of the time.  HIV transmission is less efficient.  The risk for transmission of HIV in a single unprotected sex act is about 1 transmission for every 1000-2000 sex acts (same risk for males and females).  Transmission risk is likely impacted by factors such as the sort of exposure (  vaginal, rectal, oral),  condom use, circumcision status for men, and logically, the duration of intercourse among other variables.   Whether symptomatic persons are more likely to transmit infection or not is unknown (as you might imagine, this is challenging to study) but this is perhaps a reasonable assumption. 

The analogy is that you have no doubt been exposed to others with the flu, colds or perhaps pneumonia but did not acquire the infection. 

The best way to avoid becoming infected is to use condoms consistently and correctly for all acts of intercourse.  I f you do this, since most people do not have STIs and since even most unprotected exposures your risk for infection becomes very low.  The absence of symptoms is one possible bit of evidence as to having not become infected but this too varies with different STIs, for instance in men, most gonorrhea (about 90%) is symptomatic which the majority of chlamydial infections are not.

I hope this information is helpful.  We do recommend periodic testing for persons with multiple sex partners, particularly if condoms are not used.  The frequency varies from person to person depending on partner number, partner type, condom use, etc. but is rarely re often than every 3-6 months and for most people who have not developed symptoms, an annual screening examination is typically sufficient.  EWH
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31 months ago

Dr. Hook,

 

I am simply looking for clarification with the information you provided so I could integrate it with my understanding. I have no intentions of being argumentative. I am just trying to make sense of how transmission is rare if the mechanisms for transmission exist. I presume it is because the immune system readily clears the insufficient spread or amount of the virus from the infected person. (Like your analogy with the flu, colds, etc.) However, when sufficient virus is spread, where the immune system cannot readily clear the virus, thus transmission occurs, symptoms would exist. That would mean there is a causal relationship as I am hoping for. This is my explanation that I rationalized. Can you answer if my presumption is correct, with all considerations you mentioned factored in?  This would give me the basis and comfort I am looking for in this post.

 

Lastly, a male receiving superficial oral from a woman, that is licking or sucking on testicles, for example, there is virtually no risk because there is no opening allowing for the spread of viruses as in penetration (involving mucosal surfaces) and in the case of a micro-abrasion caused by friction with an infected lesion which is not the case in this scenario. In other words, at the very least, there needs to be an opening for the spread of viruses, correct?

 

Thank you doctor. 

Edward W. Hook M.D.
Edward W. Hook M.D.
31 months ago
Final responses:

RE your statement- "I presume it is because the immune system readily clears the insufficient spread or amount of the virus from the infected person. (Like your analogy with the flu, colds, etc.) However, when sufficient virus is spread, where the immune system cannot readily clear the virus, thus transmission occurs, symptoms would exist. That would mean there is a causal relationship as I am hoping for."  This is an oversimplification.  Numerous factors influence the likelihood of transmission other than the immune system.  The transmitted organism must be viable- viability diminished with time outside the body, temperature, moisture and numerous other undefined or partially defined processes, then the organism must come into contact with susceptible cells, then the biological processes the lead to establishment of infection must occur.  All of these facts vary from organism to organism and are part of the reason, for instance, that fewer than 1 in 1000 unprotected exposures to infected partners lead to HIV infection.  Further, your presumption that symptoms would uniformly exist is again, categorically wrong.  All STIs may be present without symptoms, as well as in situations in which signs are so mild that they are unnoticed. 

Similarly, your last comment regarding "no opening" is a bit of an over simplification as well.  Friction is part of sex.  Friction may lead to micro-abrasions which facilitate transmission.  Despite that, and sometimes even in the presence of abrasions, sores or nicks from recent shaving, the fact is that licking or sucking on testicles has not be demonstrated to lead to transmission of viruses.

this will end this thread.  I hope my answers regarding the complexity of STI transmission are helpful.  I also trust that you will not need to return to this site with similar questions as I will have little more to say.  The issues of STI transmission and the presence of absence of symptoms vary on an organism by organism and site by site basis.  It is a complex topic which continues to be studies by scientists who have engaged in such studies for decades.  EWH
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