Thank you for your inquiry. From what we gather from the question, you were asking about the risk of HIV transmission through oral sex. The risk for performing oral sex and receiving oral sex are different. The scenario of performing oral sex is deemed Low Risk (evidence of transmission occurs through these activities when certain conditions are met).
Performing oral sex does meet the three components of the transmission equation. Factors that would increase the risk of transmission are sores in your mouth or bleeding gums which would increase access to your bloodstream, or sores on your partners genitals (1). Receiving oral sex is deemed to be a Negligible Risk (there is no evidence or no documented cases of HIV transmission. However, there is a theoretical possibility of transmission under certain extenuating circumstances).
It is possible to contract gonorrhoea and chlamydia by giving or receiving oral sex. Many STIs (sexually transmitted infections), such as chlamydia and gonorrhoea have no symptoms (1). It is also possible to have an HIV infection at the same time you have another STI. Having chlamydia or gonorrhoea increases your risk of contracting HIV because they can cause sores or breaks in the skin that allow the virus to enter your bloodstream (2).
It was very responsible of you to go to your health care provider for initial STI testing, and my recommendation is that you follow up with them for HIV testing.
AIDS Vancouver Helpline/Online, Rashell
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1.) CDC STI Fact Sheet
2.) HIV and STIs