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Anonymous on October 1, 2011

My HIV antibody test is positive...but the Western Blot is negative. What does this mean? Do I have HIV or not?

About 7 months ago I visited a gentleman's club in Singapore (I was there for school). I wound up French kissing one of the workers there. I did not have sex ⎼ including oral sex ⎼ and no drugs at all. I got concerned about STDs so I went to a doctor for advice. He said that French kissing is a risk for HIV and I should get tested at 3 months...but I got scared so I got tested almost every week. And all ten tests were negative until my last test at a hospital. That test was an ag/ab test called a chemiluminescence test and the document they gave me had an index number on it (2.69). They ran a Western Blot for HIV-1 and HIV-2, both of which were negative. I went back for confirmation two weeks later and got the same results but with an even lower index number (1.72). I’m so confused about these results...but I also read that false positives are rare...do you have any advice?

answered by
Lisa Oldson, MD on October 5, 2011

Thank you for your question. I can sympathize...this must be a very stressful situation for you. 

Because your results are confusing, I would first encourage you to find a doctor who specializes in HIV/AIDS to help you interpret your results. I can understand that you’re getting tired of feeling in limbo...but talking to a specialist who can look at your personal test results may help give you peace of mind. In the meantime, I’m happy to offer you a few thoughts on your situation. 

From your description, you’re at low risk of contracting HIV from deep kissing. The Centers for Disease Control and Prevention (CDC) report that the only known cases of people catching HIV during deep kissing occurred when blood was exchanged. In other words, if the person you kissed was HIV-positive and had open sores or bleeding gums, there’s a remote possibility of HIV transmission. 

As for your previous HIV tests...

Given that you had so many negative HIV tests after your possible exposure to the virus, chances are that you don’t have HIV...a total of 10 negative tests over the course of six months is very reassuring. According to the CDC, if a person develops HIV after recent exposure to the virus, the antibody test will indicate an infection in most people by 25 days after exposure...and the antibody test will indicate infection in 97% of people by 12 weeks. (Keep in mind that an antibody test includes a confirmatory Western Blot). 

That said, why you had those two very low level positive antibody tests with negative Western Blots later is unclear. Could they be false positives? Perhaps. Would another test at some point probably be a good idea? Yes. But, at this point, you may benefit from waiting a little while before you rush into another test. Talk to your doctor about doing a repeat antibody test in another 3-6 months...if you do have HIV-1, your body would very likely create antibodies to it by then. 

There’s another consideration here, too...

When an HIV screening antibody test is positive, but the Western Blot is negative, it could indicate the possibility of HIV-2. The Western Blot does not confirm HIV-2...so when an HIV-antibody test is positive, but the Western Blot is negative, a different confirmatory test is called for. This test is called an HIV-2 immunoblot. 

But keep in mind that ⎼ in the United States ⎼ very few cases of HIV-2 have been reported. In fact, since 1988 only 242 possible cases have been reported to the CDC...and only 166 of those met the criteria for HIV-2. This strain of the HIV virus is seen primarily in West Africa or in those who were sexually active there and then immigrated to another country. However, because your results are slightly atypical, the CDC recommends additional HIV-2 specific testing...so when you do your final test for HIV, you might also talk with your doctor about an HIV-2 immunoblot if you have any concerns about exposure to that virus.

Your results thus far inspire optimism. That said, people infected with HIV today have the benefit of better medications and more information about the virus than people had as little as 20 years ago. 

The good news is that doctors now think of HIV as a chronic disease that can be managed with medication. There is debate in the medical community about how long those infected today will live with our newest and best medications...but taking medications, eating well, exercising and regular follow up with an HIV specialist can go a long way to increase quality and length of life. 

Perhaps my most important piece of advice for people with HIV today...save for your retirement! 

One more thing...are you currently in a relationship and/or sexually active? If so, I encourage you to use condoms in the unlikely event that you do end up having a positive HIV test down the road. In situations like these, using condoms and an honest discussion of your situation with any current or future partner is important.

For more information, our Expert Guide to HIV + AIDS may be helpful to you. 

I wish you good luck and the best of health. 

Related info: 

Lisa Oldson, MD

Dr. Oldson is Medical Director of the Analyte Physicians Group. She is on staff at Northwestern Memorial Hospital, as well as Clinical Instructor at the Feinberg School of Medicine, Northwestern University. Her areas of expertise include STDs (with a particular clinical emphasis on herpes), women's health, preventive medicine, diabetes, obesity and weight management, and mood and anxiety disorders. Dr. Oldson was educated at Rush Medical College and completed her residency at Rush-Presbyterian-St. Luke's Medical Center in Chicago, IL.

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