I am an MSM bi sexual man who recently did something which I would appreciate your advice and risk assessment.

Here's what went down, I agree to meet up with a male 37 year identifying as gay for mutual masturbation and oral sex. I asked his status and was told it was negative. 

When I attend his house I found him living in a shed in and he didn't look like a completely honest and "clean" person (his living situation was poor and squalid) there was also drug equipment (bong and weed) visible which at the moment I over looked.. he was naked and I notice a large red rash atop his crack and between his cheeks, other then that he looked unmarked. We engaged is very brief like 2 to 5 seconds oral sex and I then masturbated over him to completion as he stroked his own penis and rubbed his ass he did not cum. 

I am concerned about HIV and syphilis. I understand that syphilis is on the rise in South Australia but remains mostly in the aboriginal population and MSM. Should I be worried about his rash? What are the real risks and should I be tested? 

Thanks in advance.

I also acknowledge there is a risk of gonorrhea, chlamydia and NGU.

I can understand your concern:  you were misled, whether intentionally or not, by your partner; and both he and the setting sound pretty unpleasant. However, a disordered or unhygienic lifestyle does not in itself suggest especially high risk for HIV or other STIs. A rash of the sort you describe, including its location, is much more suggestive of a hygiene issue or perhaps yeast infection, but it doesn't sound at all like the rash of secondary syphilis. The exposure itself was low risk -- oral sex isn't completely risk free, but very low risk compared with unprotected vaginal or anal sex; and especially low risk with such brief contact. And hand-genital contact is risk free. Finally, people usually are truthful when asked directly about HIV status.

Next steps? Mostly for reassurance, but not because of risk level, you could have urine and throat swab tests for gonorrhea and chlamydia; and, after a few weeks, blood tests for HIV and syphilis. Or if you're on speaking terms with your partner and he would agree to be tested, you could seek testing together. If you both are negative for all pertinent infections, you'll both know you were not at risk, without need for delayed testing.

Also consider at least speaking and perhaps visiting your nearest federally supported sexual health centre. Australia's SHCs are the world's best network of such clinics and for expert STI knowledge. While you are correct (according to my understanding) about the geographic and population distributions of syphilis in your country, a nearby SHC is likely to have specific advice about partners and settings such as these. (If you're in or near Sydney or Melbourne, their SHCs are the best of the best -- but in my experience all are outstanding.)

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

HHH, MD

Would you say I could resume protected sex with my regular partner or should I wait for testing? Unfortunately I'm unable to get the male partner to test, he says he's clean and negative. I guess I can assume that my risk was truly small and move on? 

it has been approximately 2 weeks today since this incident and I have experienced on and off headaches, dizziness, exhaustion, night sweats for the last week and now have diarrhoea.. the nurse at the clinic advised that these are symptoms of HIV? I've managed to get myself into a SHC where they said I can get testing done specifically RNA HIV testing whatever that is? When will I know for certain if I am clear? I'm so worried now! 

"Southern part" is a big area of Australia -- but since you don't say Melbourne, maybe Adelaide? I've been to the Adelaide SHC, which is excellent. Still, the fact is that symptoms almost never are useful indicators for or against a new HIV infection. Innumerable symptoms common in any infection also can occur with ARS (acute retroviral syndrome, i.e. new HIV infection) -- and even in people at maximum risk and with typical symptoms, the large majority have other explanations for those symptoms. Even though you list some symptoms that can occur with ARS, you don't mention the usual pattern, which is a combination of fever, sore throat, enlarged lymph nodes in several body areas (neck, groin, armpits), and skin rash. In view of the exposure described, and with a partner who probably isn't infected (most people don't lie about HIV status when asked directly), I will be very surprised if you test positive for HIV.

Yes I am in Adelaide and will be attending a specific clinic for MSM. They've confirmed that an RNA test is best as will give me some resolve given my symptoms and yes I'll need to do another test 4th gen? In 2 weeks post this.. 

I will keep you posted and thank you for your final statement you've talked me off the ledge.

Normally threads would be closed at this point. But you seem to want to report your next negative result as well -- so I'll leave it open. But no more comments until then-- OK?