HomeAnswersHIV/AIDS specialisthiv risk factorsIs a negative HIV screening test at 36 days conclusive?

Is a negative HIV screening test at 36 days conclusive?

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The following is an actual conversation between an iCliniq user and a doctor that has been reviewed and published as a Premium Q&A.

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Published At February 12, 2018
Reviewed AtJuly 12, 2023

Patient's Query

Hello doctor,

I had a low-risk event (no penetration but exchange of fluids through fingering and immediate masturbation). At 26 days, I received a PCR (Polymerase chain reaction) /RNA (Ribonucleic acid) test that came back undetectable. At 30 days, I felt a small posterior cervical lymph node which I know is connected to HIV. At 36 days, I received an ab/ag test (blood drawn from a vein) and that too was non-reactive. Would you consider these conclusive? I just cannot get over the lymph node and after digging have found two more small ones in my cervical chain. Should I get tested again? I have a family and want to protect them.

Answered by Dr. Sushil Kakkar

Hello, Welcome to icliniq.com.

I have noted your concern. A fourth-generation HIV screening test (antigen /antibody) is considered conclusive at four weeks. So, a negative test at 36 days is conclusive. Regards.

Patient's Query

Hello doctor,

Thank you for the quick response. I have read that but also read conflicting reports about six weeks. Either way, I assume the RNA test being undetectable prior to this would confirm. Am I correct in assuming if the RNA was down it would be because of antibodies? I am afraid that at 36 days antigen could have disappeared but antibodies did not develop yet. Moreover, what could be the cause of these posterior cervical nodes? I am not making them up, two doctors examined and agreed this was the correct node, but they both were not sure if they were swollen. Definitely palpable though and cervical lymphadenopathy seems to be very high on symptoms checklist.

Answered by Dr. Sushil Kakkar

Hello, Welcome back to icliniq.com.

Definitely, a negative RNA PCR at 26 days is very reliable. It has a short window period of 9-13 days and is therefore considered reliable two weeks onwards after a risk exposure. However, a negative RNA PCR is not a confirmatory test and should be followed up by either a 4th generation HIV antigen/antibody screening test at four to six weeks or an HIV antibody test at four weeks and then again at 12 weeks. Though at four weeks, a 4th generation HIV antigen /antibody screening test is considered conclusive, many sexual specialists take it conclusive at six weeks. The P24 antigen is detectable between one to eight weeks after infection. So, it persists for one to two months after it first appears. Antibodies start developing by two to three weeks after infection and about 95 % would have detectable antibody by four weeks and 99.9% by 12 weeks. So at 36 days both P24Ag and anti-HIV antibody should be present. Cervical lymph nodes are considered significant only if they are >0.196 inches in size. Local causes like a bacterial skin and soft tissue infection may cause swollen cervical lymph nodes. If they measure >0.196 inches I suggest you take an empirical course of an oral antibiotic either Amoxicillin or Cephalexin for a week. Consult your specialist doctor, discuss with him or her and start taking the medicines with their consent. Regards.

Same symptoms don't mean you have the same problem. Consult a doctor now!

Dr. Sushil Kakkar
Dr. Sushil Kakkar

Dermatology

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