Expert: Terry B - 4/13/2008

Question
I have 2 questions.
1) I was told its not 100% possible to tell immediately after unsafe sex by HIV test. There is a time lag of at least 6 weeks (longer in some cases) to be certain if a person is HIV +. Now my question is that when someone donates blood in emergency situations, how is it tested and made sure that person does not have HIV+.
2) HIV +  is spread via milk to kid from a mother. and I assume that if that milk is fed to a person then also HIV+ will spread. But why is that HIV+ does not spread via Oral sex (if there is no cut in mouth) but it does via milk.

Answer
Dear Heerok:

Peace.  I replied earlier but lost connection, apologies for the delay.  Excellent questions.  I can only answer in relation to what common practices are among accredited blood banks; emergency situations may cause deviations should blood supply not be available.

Collection of blood from donors occurs over a period of time - the use of donated blood or blood products in time of emergency usually draws upon sources collected prior to that emergency.  Collection of blood from donors begins with an invitation and questionnaire citing some of the most common risks for possible HIV (and Hepatitis) transmission; a "yes" answer to these allows for pre-screening prior to donation.  After blood is taken from a donor, the donor is again asked to review the risk profile, and allowed to have their blood discarded if on further reflection they remember some risk to a potential recipient of their blood.  This allows for a voluntary screening that reduces the number of potentially infected blood units.

Following collection of the blood, the blood is then tested (tests and methods vary but reflect some of the most advanced techniques) for the presence of HIV antibodies or, in some cases, antigens that might signal an infection like HIV.  These are "Highly Sensitive" tests that cast a wide net for things like HIV - including other infections that produce similar antibodies.  As a result, almost all HIV tainted blood is identified and destroyed, along with other suspect samples.  If this were a counseling and testing situation, a second test, "Highly Specific" would be performed to identify whether the antibodies were actually HIV antibodies or something else.

HIV can be transmitted by oral sex, but it is rare.  In the case of breastfeeding, one is looking at ingestion of larger amounts of potentially infectious fluids over a longer period of time.  One could argue that if a person were to have unprotected receptive oral sex every few hours over a long time frame, the rates of infection might approach those for breastfeeding risk.

I hope that helps.  For more on the blood supply and safety, you can research at www.cdc.gov, www.thebody.com, and/or www.avert.org

Best to you and yours,

Terry