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?

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

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