[Question #7699] Question regarding Test Results for HIV and Syphilis

53 months ago

Hi, I would want to thanks for all the help that the forum and all doctors provide to the people who needed help to release their anxiety.

Here will be my questions, please help answer it as detail as possible, since my anxiety will easily let me drill on some details a bit.

1). I’m going to take the HIV P24 combo test (4th generation) and the syphilis T-pallidum antibody + VDRL test today, it is now 28 days since my possible exposure. If it comes out negative can it be conclusive for both that I didn’t catch HIV or syphilis?

2). I actually took the RNA PCR test on the 25 day, and it came out not detected, will there be any chance that the P24 combo test results will change? (I’m in Hong Kong, and there’s only 1 case of HIV2 reported since before).

3). If the tests I took today are not conclusive, when should I retest again for conclusive results? And what will be the percentage that I can rule out for today’s test?

4). I’ve took the hepatitis B vaccine since I’m a child, and I checked for the anitbody last year it is still around 600, so I need to test for hepatitis B too? Or am I safe from that?

53 months ago

And for more updates: I’ve been taking Augmentin (amoxicillin) for 14days (ended around 1.5weeks ago), will it affect the result for syphilis?

Edward W. Hook M.D.

53 months ago

Welcome to our forum and thanks for your kind words. You say nothing about the exposure that has you concerned about HIV, syphilis and perhaps other STI ‘s. And I’ll go straight to your questions.

1 & 2. HIV test results first. Until several years ago fourth generation HIV tests were thought to be conclusive at four weeks. More recent data however suggest that a very small (a fraction of 1%) proportion of persons who have acquired HIV have tests which become positive in the interval between four and six weeks. Official recommendations are that at six weeks fourth generation tests are absolutely conclusive. The fact that you have a negative HIVPCR taken at day 25 however makes the likelihood that your test will become positive effectively zero. When your fourth generation test comes back negative I would Consider the results to be conclusive and see no reason for further testing.

Your syphilis result is also conclusive. While it can occasionally take up to 6–8 weeks for Syphilis blood test to become positive, the 14 days of amoxicillin that you have taken would be curative if you had Syphilis. If you’re Syphilis blood tests are negative at this time they will remain so.

3. After your most recent test, I see no reason for further testing for either HIV or Syphilis.

4. Your hepatitis B vaccine provides lifelong protection against infection. Your antibody levels verify this. There is no reason for testing for hepatitis B.

I hope this information is helpful to you. If there are any further questions about this matter or need for clarification please feel free to use you were up to follow up questions for that purpose. EWH

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53 months ago

Thank you so much for Dr. Hooks keenly reply. So I guess I’m clear for both HIV and syphilis. But there’s still one confusion for me.

Since you said sometimes syphilis test will take up to 6-8 weeks, why would my result be conclusive? (The amoxicillin I took actually isn’t for syphilis, I got a swollen lymph node 4 weeks ago, and the amoxicillin is for the swollen lymph node to be cured).

And also, since I have no symptoms for gonorrhea or herpes these few weeks, can I also rule out the infection for both?

The last question is that my possible exposure is actually a low risk to no risk exposure, it is just receiving blow job from a massage parlour, is there any chance that I’ll catch genital warts?

Edward W. Hook M.D.

53 months ago

Thank you for the additional information on your exposure. Receipt of oral sex is among the lower risk sexual activities for acquisition of STIs. There are no proven cases of HIV which have been acquired from receipt of oral sex. Similarly acquisition of syphilis from exposures of the sort you describe are so rare as to be the subject of anecdotes. The major STI‘s for which a person is at risk for from receipt of oral sex are gonorrhea and perhaps herpes.Most, but not all gonorrhea is symptomatic and so it might be advisable for you to have a urine test for gonorrhea and chlamydia to be 100% sure you were not infected. As far as herpes is concerned, how do you acquired herpes you would have most likely develop symptoms within 10 days of exposure. You can presume you were in the clear for herpes.

I would not be concerned about acquisition of HPV from receipt of oral sex either. This to is extraordinarily rare.

Your result is conclusive because in the unlikely circumstance that you had acquired syphilis you had taken curative doses of medication which would arrest development of the antibodies which would be detected in the Syphilis blood test.

Hope this helps. EWH

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