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How long does it take for HIV to show in the blood?


Dear Doctor,

How long does is it take for HIV to appear in one’s blood after he or she has had a sexual encounter with someone who is HIV-positive? I had unprotected sex with a woman and I later found out she was HIV positive four months ago but have tested negative each time. I have been testing monthly.



Dear Anonymous,

When HIV enters the blood of a new host, it takes three to 12 weeks for the body to develop antibodies against it, which can then be detected by the HIV test you have been doing. This is the so-called window period, during which someone who is infected may test HIV-negative and yet he or she has HIV, yet he or she can infect others.

That is why when you go for an HIV test and you test negative, you are advised to go back for another test after three months. HIV can, however, be detected during this period by using another test known as the RNA-PCR test, but not all testing centres can do this test.

You need to seek counselling from an HIV counsellor because you seem to still exhibit risky behaviour by having unprotected sex with someone whose HIV status you do not know.

Because of the normalisation of the epidemic, where people no longer look at HIV as an immediate cause of ill health and lack of personalisation of the HIV risk, many more people are getting infected with the virus.

If you tested HIV-negative four months after the exposure, you may have survived infection. However, you should never take chances.

All people who are HIV negative should always assume that any person whose HIV status they do not know is positive and take precautions to protect themselves. That is the only way we are going to eradicate HIV from our midst.


All articles are republished on AEGIS by permission. Material may not be redistributed, posted to any other location, published or used for broadcast without written authorization from Managing Director/Editor-in-chief, The New Vision, P.O. Box 9815, Kampala - Uganda, Tel/fax: 256-41-235221, E-mail: 

Information in this article was accurate in May 14, 2013. The state of the art may have changed since the publication date. This material is designed to support, not replace, the relationship that exists between you and your doctor. Always discuss treatment options with a doctor who specializes in treating HIV.