[Question #3401] Risk of transmitting an STI through urine or Semen

38 months ago
I am a 31 year old male that was last sexually active about 10 months ago with a female. The type of sex performed was penile/vaginal intercourse. During that last sexual encounter, protection in the form of a condom was used, but I did not know the status of the female in terms of STIs (it was a one-night-stand). I did not get tested until a few days ago (a basic STI test) and am currently waiting for the results. I haven't been sexually active with another individual since. I have not experienced any symptoms pertaining to an STI. However, I worry that I could possibly have contracted an STI without knowing it. Furthermore, I am concerned that, if in fact I do have an STI, I might be able to transmit it in ways other than sexually. Two scenarios are bothering me. First is that a potential STI could be transmitted through my urine. I notice that after I urinate, a few drops of urine are usually collected in my underwear. I also sometimes neglect to wash my hands after I urinate. I worry that if I manage to get some urine residue onto my hands and then transfer that residue to an inanimate object like a doorknob or light switch, I could possibly transmit and infect another individual with a possible STI. Similarly, the second scenario involves semen from masturbating. Sometimes after I masturbate, I will get a little semen on my hands or have some semen deposited into my underwear. I sometimes neglect to wash my hands or worry that I haven't washed off all of the semen.  Again, I am concerned that if I manage to get some of the semen residue onto my hands and then transfer that residue to an inanimate object, I could possibly transmit and infect another individual with an STI. Is this possible? I heard that a virus like Hep B can survive for up to 7 days outside the body. Let's say I do have Hep B (although I'm pretty sure I was vaccinated for Hep B at around age 10). Can I transmit the virus or any other STI by way of the scenarios mentioned above?

Edward W. Hook M.D.
Edward W. Hook M.D.
38 months ago
Welcome to our Forum. I'll be glad to comment.  Given the nature of your last sexual contact (condom protected) and the absence of symptoms at this time I anticipate that your test results will show that you do not have an STI.  Although you did not ask, I can assure you that your test results will be reliable.

Regarding your questions, they are similar and in the unlikely chance that you are infected, there is no known risk of STD transmission through the transfer if infected material (urine, ejaculate, other) is transferred on a person's hands to another.  Mutual masturbation when persons actively get each others' genital secretions on each other is considered safe sex and the situations you describe not only involve transfer of smaller amount of infected material from person to person but also introduce a time element.  Since direct contact is not a risk and since STI pathogens rapidly become non-infectious on drying and exposure to the environment, IF you were infected (unlikely) there is no reason for concern that you might have transmitted infection.  This is the case both for bacterial and viral STIs.

Finally, with respect to your statement that hepatitis B can survive outside the body for 7 days, please remember that micro-organisms become non-infectious before they are completely dead.  Statements regarding long term ability to recover micro-organisms from the environment should not worry you.

I hope these comments are helpful.  As I said, the scenarios you describe are no risk for STI transmission.  EWH
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37 months ago
Thank you for your answer. I'm also wondering if the same applies to infections or diseases that are not primarily considered to be STDs. For example, I've read that something like hepatitis A is often found in contaminated food or drink and therefore enters a person orally. I've read that transmission of Hep A is normally by way of something like fecal matter and poor hygiene and sanitary conditions. But can it be transmitted through genital secretions or urine? I haven't been vaccinated or tested for Hep A, so I don't know if I have it, but, let's say I do. Let's also say I don't wash my hands after using the toilet or masturbating. Is it possible to transmit a pathogen normally not considered an STD like Hep A through urine or semen? Does the same advice that you gave in the previous answer about micro-organisms becoming non-infectious before they are dead also apply to this example? I'm wondering if this extends to most infections and diseases?
Edward W. Hook M.D.
Edward W. Hook M.D.
37 months ago
Different sorts of infections are transmitted in different ways.   As you mention, hepatitis A is transmitted though ingestion (often unwittingly in contaminated food or water) of the virus.  Hepatitis A is an STD when there is transmission of fecal material to a person's mouth during sexual activity which might include analingus or oral sex on a penis after it had been inserted in the bottom of a person with hepatitis A- most hepatitis A however comes from ingestion of contaminated food or water.  There are no data to suggest that exposure to urine or genial secretions leads to hepatitis A transmission.  STIs are also not known to be transmitted through contact with clothing, including underwear which has been contaminated with urine or genital secretions.  I hope this information addresses your concerns.  If not, you have one follow-up question remaining which you might use to seek further clarification.  EWH
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37 months ago
I believe this question is similar to the first, but I would like to gain clarification. Let's say I masturbate at home. I collect most of the ejaculate into some tissue paper and discard it. However, there is some residual ejaculate that soaks into my underwear. I then immediately leave the house and go to a coffee shop. While at the coffee shop, I use the public washroom that's available to urinate. While urinating, I notice that some of the ejaculate still hasn't dried and I inadvertently get it onto my hands. After urinating, I go and wash my hands and transfer some of the ejaculate to the faucet. Perhaps I don't wash my hands well enough and transfer some of the ejaculate to the door knob as I exit the bathroom. Does the fact that the ejaculate has not completely dried affect the risk of transmission to another person if I did have some disease? Conversely, would I be more susceptible to contracting a disease (I touch some wet contaminant/disease as I'm entering the bathroom (ex. touching the light switch)  and then transfer that contaminant/disease to the still-wet ejaculate as I go to urinate (I'm reasoning that the still-wet ejaculate would somehow make it easier for the contaminant/disease to enter my body)? I feel that I am incorrectly applying the characteristics of things like syringes in their ability to transmit pathogens to these open air environments. Lastly, if a female were to enter the bathroom immediately after me, would there be any risk of pregnancy from the still-wet ejaculate that might be on the toilet or faucet etc.?
Edward W. Hook M.D.
Edward W. Hook M.D.
37 months ago
You are assuming that these infections are more easily transmitted than is the case.  The situation of transfer of undried ejaculate to another person, directly or indirectly is not going to lead to transmission of any STI.  Similarly, your ability to make a non-contraception woman pregnant through inadvertent indirect contact with ejaculate is not realistic and should not concern you in the least.  STIs (and pregnancy) are transmissible only through DIRECT contact and to worry about the sorts of indirect exposures you are suggesting is just not a realistic possibility. 

This is my 3rd response to your series of questions.  As a result, as per Forum guidelines, this thread will be closed later today and there will be no further answers.  I hope that the information I have provided will be useful to you.  STIs are harder to transmit than you think and are not transmissible as a result of exposure- direct of indirect to ejaculate.  EWH
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