HIV tests

[Dyingwithanxiety]

I have some more questions regarding tests..This is my second question. I couldnt able to post it along with my previous queation..

Questions are
1) What is DUO tests? What are the tests included in it? What is the best time to go for this test after risk of exposure? How accurate the results are?
2) What is Nucleic acid test(NAT)? How this is different from p24 anitgen test? Which is more effective test p24 antigen test or NAT? What is the best time to go for these tests after risk of exposure? How accurate the results are?
3) How early most people get diagnosed for HIV positive if they have normal immune system?
4) When HIV diagnosis exceed more than 6weeks? How rare this event is? Is it in the case of week immune system? Does smoking affects or weakens immune system? In my CBC tests WBC count is 7400. Does this mean I have normal immune system?.
5) Have anyone diagnosed with positive in 12week test eventhough their 6week test is negative? How rare this event is?

I know I have asked so many questions. I didnt have sex education so please help me. The articles I have gone through in internet have different opinions. I dont know how to get/put these things together. I have gone through the forums here and doctors replies are good. Thats why I decided to get registered here.

Like most people questions because of anxiety and panic/stress is
1) Does 6week test is good using Rapid antibody test? Is there anyother test which can identify early? Why we say 6week test is almost conclusive?

Becuase this is the only place(Medhelp) where I have heard 6week normal standard test result is almost fine and it is very rare that continued your 12 week result will say differently. I dont know how you say or based on what you say this is rarity?


Advance thanks for your help..

[Edward W Hook, MD]

You are repeating your earlier quesitons

1.  Some people turn positve as early as by two weeks but that really doesn't matter and is not the important question.   The important question is how long until results are completely reliable.  As I said earlier, by 8 weeks virtually everyone who is going to have a positive test will have positive tests  

2.  IA Western blot is not needed.  Eithe a rapid test or an ELISA will do the job equally well.

Questions 4 and 5 are also already answered,.  There is no reason for you to worry about your immune system and smoking does not meaningfully weaken the immune system.

If you ask questions already answered again, they will be deleted without comment.  EWH

[Edward W Hook, MD]

There is a character limit on our site to keep people from asking overly long questions which would keep us from helping others.  I will briefly address these additional questions:

1.  The DUO tests are highly accurate tests which test for both the HIV p24 antigen and HIV antibodies. Because it tests for more than just the antibodies, definitive test results are available sooner than with antibody tests.  Most experts agree that a negative DUO test at 4 week following exposure is proof that a person did not get HIV.
2.  A NAAT test is a nucleic acid amplification test like a PCR which is more sensitive than other tests.  In fact it is so sensitive that it causes relatively frequent false positive results.  In general we do not recommend HIV PCR testing for diagnosis is HIV infection for several reasons.  While the PCR is likely to become positive more quickly than other antibody detection tests (i.e. usual blood tests), at the present time the blood tests are becoming more and more sensitive and detecting infection earlier and earlier so that the time difference in detection between PCR test and antibody detection tests is becoming smaller and smaller and at present is, in general only a week or two.  In addition the time course over which the PCR tests become positive is less well described than for the blood tests and, as a result, it is difficult to make a definitive statement on what a negative PCR test means at any time within a few weeks of exposure to a HIV infected or possibly infected partner.  PCR tests are also more expensive than regular antibody tests.  Finally and most importantly, the false positive rate for PCR tests (i.e. a positive result in persons who do not have HIV) is higher than for blood tests.  Each of this on this Forum have seen a number of people who were worried needlessly because of false positive tests. For all of these reasons, we rarely recommend testing for HIV diagnosis using PCR.  
3.  Depends on the test.
4.  It is uncommon.,  As I answered in your earlier question, you need to worry.  Your tests are reliable. the CBC is a crude measure of immune function.  If you are healthy you should not worry that your immune system is weak.
5.  This is a silly question.  It has happened very, very rare in persons at high risk. You are not at particularly high risk.

1.  this is a repeat question. It has been answered.

Finally, Dr. Handsfield and I have been taking care of persons with and at risk for STDs, including HIV since before the HIV epidemic began.  If you do not want to believe us, that is your choice. We do not debate with other web sites.  EWH

[Dyingwithanxiety]

Thank  you very much doctor.

Your comments are very useful and thats all I have for now..

[Dyingwithanxiety]

I am just so so happy I got response from wealth of knowledge.. You just have to see my face. I am definitly in the right place..

I have couple of things  to clarify from your answers

1) If it is normal rapid antibody test, how early the HIV infection can be diagnosed after the rsik of exposure?.
2) Which is a better test to go after 6weeks, is it rapid antibody test from blood or ELISHA or western blot test?

Special question from happenings to me
4) If CBC and DC blood tests are normal(Within range), then HIV infection should be diagnosed at 6weeks after risk of exposure, isn't it?
5) Does smoking causes sore throat and dry cough? Does it weakens immune system?

Thank you very much for your answers in advance..