I had unprotected vaginal sex with a female I didn't know.  The morning afterward, I noticed a small lesion on my penis resembling a scab.  This went away after a few days.  About 2 weeks later, I developed a painful small shallow ulcer on my soft palate.  This lasted appx. 10 days.  During that time, I also experienced myalgia in my thighs which lasted appx. 2 days.  I was very nervous about ARS.  I was tested for HIV with an 4th Ag/Ab test and a quantitative RNA test at around 54 days post potential exposure.  These were both negative.  I was retested with a 4th gen Ag/Ab test at 91 days post potential exposure which also resulted negative.  It is now nearly 6 months post-potential exposure.  I have not had any new potential exposures since the initial event.  Would you recommend retesting at this time?

Thank you   

First to your main question:  The HIV AgAb tests are among the most accurate diagnostic tests ever developed, for any medical condition. When done 6+ weeks after the last exposure, the results always are conclusive and outweigh all other factors:  no matter how high the risk of HIV at the time of exposure, and no matter what symptoms are present, the test result rules. Your negative result at 54 days proved you did not catch HIV during the sexual exposure mentioned. The second test confirmed that result, but was superfluous. Do not have any more HIV tests. If your symptoms continue or you otherwise remain concerned, see a doctor. But you can be sure you do not have HIV.

Ancillary comments:  No STD can cause symptoms in under ~36 hours, and no STD starts out with a scab. Whatever you had that morning, it was present before the sexual events the night before. However, the most common cause of a penile sore that leaves a scab is genital herpes, and the timeline you describe -- the scab clearing in a few days -- also is consistent with herpes. Have you ever had previous penile blisters or sores? Or diagnosed with herpes? If not, you should keep that possibility in mind, especially if you ever have a similar occurrence in the future. If any doubt, a blood test for HSV might be warranted.

"Painful small shallow ulcer" anywhere in the mouth, including the soft palate, is a typical description of aphthous stomatitis, commonly known as canker sore. It's not an STD, and although oral ulcers can occur with ARS, this is rare, and ARS would rarely cause only a single lesion. ARS also would not cause only an oral ulcer or, for that matter, myalgias limited to the thighs.

As noted above, your exposure probably was low risk for HIV, because a) HIV is rare in most sexually active women and b) when present is transmitted an average of once for ever 2,500 episodes of unprotected vaginal sex, according to an estimate published by the Centers for Disease Control and Prevention (CDC). That said, I certainly would advise you to get into the condom habit for future casual or otherwise high risk sexual encounters. You also might consider routine STD testing, if not yet done -- i.e. urine gonorrhea/chlamydia and a syphilis blood test.

So all things considered, you can put aside any concerns about HIV. But it sounds like you at least should be on the lookout for symptoms of possible recurrent genital herpes and perhaps be evaluated with an HSV blood test. I hope these comments are helpful, and that they are reassuring in regard to HIV. Let me know if anything isn't clear.

HHH, MD