Last week Used toilet at a fuel station.  It was kind of dark with no proper lighting. I was holding urine since long. So the moment I saw the fuel station I rushed inside the washroom. The seat looked clean. As I was holding since long I didn't bother to look inside toilet commode bowl. As I sat, I saw something on the commode bowl. So I used mobile light to check and to my utter shock it was blood(WET) and by the time I could react my urine fell on it and washed it down the commode hole(Drain). While the blood was being washed down the drain, my urine fell on blood stream again. 

Blood on toilet bowl (toilet sink / basin) was  somewhat like 3-5 drops of blood clustered together at a point on the bowl of the commode toilet. I had to stretch my thighs a bit more while urinating as the width of commode seat was bigger compared to what is normally at home.  The temperature would have been around 25 degrees celcius and it felt humid also.It looked somewhat a busy fuel station, however I do not know when the last person had used the washroom before me.

I am a 20 year female with no sexual relationship till now.

1.What is the risk of HIV if blood had backsplashed inside my vagina hole or genital mucosa or anus/rectum.

2.I didn't feel like touching anything. So after urination I didn't wash my private parts. So my worry is if blood had been backsplashed inside vagina Or anus and then it might have rubbed against the mucuous membrane inside vagina Or anus other female genital parts/genital mucosa. What is HIV risk in this scenario. 

There is a long history of concerns about transmission of STIs and HIV via contaminated public restrooms and similar facilities -- going back to the 1800s if not earlier. Howver, it never happens -- or so rarely that any risk can be disregarded. (An adolescent type joke among STI experts is to answer the question "Can I catch an STI in a public toilet?" is "Yes, if that's where you meet partners for sex." In distant past history, physicians sometimes told women with STIs (especially syphilis) that they may have caught it in a public toilet, but always that was just a way of male physicians protecting their infected patients' husbands from accusations of infidelity.

There has never been a scientifically case of HIV or other STI trasmitted by contact with a contaminated environment, whether in a toilet or anywhere else. Not enough virus or bacteria can survive long enough and in sufficient numbers to transmit infection. And people who use public toilets are no more likely to have HIV or other STIs than anyone else -- that is, the chance an infected person left contaminated blood or genital fluids behind in the toilet is extremely low. To your numbered questions:

1. Thre is no known risk at all from "backsplash" of contaminated toilet water, no matter what body parts it may contact.

2. You would not have raised the risk by wiping normally.

3. This also has never been known to result in any STI.

To avoid worrying, I would suggest using common sense protection when using toilets used by other persons (not only public toilets, but those in friends homes, toilets shared by roommates or other housing companions, etc; and wash your hands afterward. These measures mostly prevent things like colds and flu, not STIs -- but still this might give you more confidence about STI risks. But really, your concerns have no basis in scientific fact. Don't worry about it!

I hope these comments are helpful. Let me know if anything isn't clear.

HHH, MD

Thank you sir for your detailed answer. It has helped me a lot, however I would like to ask some follow up questions so that there is no confusion on my part. My only concern is risk of HIV in the mentioned scenerio due to social stigma attached to it. 

1 . When you said "or so rarely that any risk can be disregarded". Were you talking about STI in general or Hiv in particular and you were talking about HIV then Under what circumstances has there been rare transmission of hiv via contaminated public restrooms and similar facilities. Can my exposure put me in that rare category. Do I have any risk and whether I need a test. 

2.In your answer 1 you said " There is no known risk at all from "backsplash" of contaminated toilet water", however I did not ask about backsplash from drain (where toilet water finally makes its way to) of the commode. I asked about backsplash when urine fell on blood while the blood was still on commode bowl/sink.What is hiv risk in this case. 

3.Is "No known Risk at all" Equivalent to "No risk". especially in my case. 

4.In your answer 2 you said "You would not have raised the risk by wiping normally." However I did not wipe it with tissue or anything. As I said that I did not wash my private parts as I didn't feel like touching the jet spray. So my question was if suppose blood had been backsplashed inside of the vagina Or anus or labia or genital mucosa and then it might have rubbed by itself from inside for e.g. let's say vagina's inner membranes or if splashed on labia and then while walking it might have rubbed against the skin or my innerwear etc. What is the risk in this case. 

5.Finally in your closing statement you said "These measures mostly prevent things like colds and flu, not STIs -- but still this might give you more confidence about STI risks." It's a bit confusing like it may appear that whether or not we use these measures STI is not preventable under these circumstances. 

6.Since I did not wash my private parts after this incident, would it increase my risk of hiv, if any in this scenerio. I mean would washing / no washing of my private parts make any difference as far as HIV is concerned. I would like to highlight that I follow the general hygiene, however on this particular occasion I did not. Had I other option, I would have not used this washroom at all in the first place. Since I was on a highway and I was holding my urine for long with no other washrooms nearby, I had no other option but to use it.

7.What is final risk assessment for HIV considering all the things and do I need a test.

8.Do I have anything to worry about even in the least?

1) HIV and all STIs.

2) No "backsplash" from any source is a significant risk.

3) There are few absolutes in biology or medicine. Terms like "virtually no risk" or "risk can be disregarded" may not mean truly zero, but it does mean risks perhaps equivalent to the possibility of being killed by a meteorite. The risk is not zero, but I would not advise taking any steps to prevent it.

4) You are overthinking all this. All these details make no difference. Still zero risk for HIV and other STIs -- or at least low enough risk that in all human history, no such cases are known to have happened.

5) Good grief. This was just a supportive, confidence boosting statement. If you don't understand it, read it again.

6) If there has never been a known case, anything you do will neither raise nor lower the near zero risk.

7) "What is final risk assessment for HIV considering all the things" Zero! ..." and do I need a test?" No, you do not.

I am a data science professional and I know that the word "rare" is very generic because some use this word when the chances are 1℅ while others use it for 0.001℅. Of course there are the things like sample size, precision that one wants etc. And that's why your answers are a bit unclear to me as far as my exposure is despite the fact that I am not sure whether the splash actually landed on my genitals or not. 

Furthermore, with the advancement of technology, scientists can very well predict the chance of meteorite falling on the our planet and advisories are issued well in advance. I am debating with you sir but just saying. Of course my age is not even half your HIV expertise. 

1.Your statement "Trust me in this: You will never get HIV until and unless you have sex and share drug injection needles. The exceptions are too rare to worry about. " This could have been a great life mantra as far as Hiv is concerned especially for people like us who are afraid of Hiv from indirect blood contacts. Could you please tell me about the exceptions that you are talking about so that we (me as well as other reading answers on the forums) may be informed about the sort of exposure that may create a risk of Hiv. And under what circumstances have these exceptional cases of Hiv occurred

2.In your reply to question 6, you said "near zero risk" And in reply to question 7 you said "zero risk" and in reply 8 also "nothing to worry about even in the least. What is the actual deal as far as my Hiv risk in the mentioned scenerio is concerned. 

Sorry sir for the above questions, but expert opinion would really matter a lot to me. 

2. From my initial reply above:  "Terms like "virtually no risk" or "risk can be disregarded" may not mean truly zero, but it does mean risks perhaps equivalent to the possibility of being killed by a meteorite. The risk is not zero, but I would not advise taking any steps to prevent it."

It doesn't matter if the splash you felt contained blood, urine, both, or neither. No risk for HIV.

That completes the two follow-up comments and replies included with each question and so ends this thread. I hope the discussion helps you gain an understanding of reality. Best wishes and stay safe.