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notanonymous
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Reged: 04/19/02
Posts: 176
Regarding First vs. Third Generation
      #37770 - 08/02/02 12:00 PM

this was taken from one of the articles posted earlier and addresses the issue that was brought up on the Hotline thread about 1st generation prolonging window to 6 months.

"When whole-virus–lysate enzyme immunosorbent assays (EIAs) were used to screen blood donations from 1985 through 1990, the average length of the window period was 45 days (95% confidence interval [CI]=34–55 days) (3). The average window period of the most sensitive contemporary recombinant protein-based EIA for HIV-1 and HIV-2 antibodies is now 20 days less (4), yielding an average infectious window period of 25 days (95% CI=9–41 days)"

hence, verifying what jackie said about 1st generation does not necessarily equal 6 months.

95% @ 34-55 days vs. 95% @ 9-41 days. both 95% way before 3 months.

http://www.ama-assn.org/special/hiv/treatmnt/guide/rr4502/intro.htm



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Anonymous
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Re: Regarding First vs. Third Generation new
      #37777 - 08/02/02 01:19 PM

Please note what Confidence Interval means for a definition go to :http://www.cas.lancs.ac.uk/glossary_v1.1/confint.html#confinterval
Basically 1st generation window avearge was 31-55 days this does not mean that 95% detection by that time period. In other words the lower end of the avearge is 31 days and the higher 55 days. meaning that AVERAGE or 50% will test positive by 55 days at the most. Where does that put tyhe other 50%? Propably at 3 to 4 months possibly 5 months. That's why the CDC has the 6 month rule. Some clinicians use 2-4 month rule for seroconversion. This pretty much covers all generations of tests. Hope this helps



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Anonymous
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Re: Regarding First vs. Third Generation new
      #37780 - 08/02/02 02:35 PM

Bottom line folks Most US labs use 1st Generation EIA's these as well as 2nd Gen detect Igg antibodies which are produced AFTER Igm AB. The reasom the 3rd Gen. is more sensitive is because it can detect Igm as well as Igg. Now after you initially get infected the body starts producing Igm right away (the same w/ all virusus)They become prevelent enough for the 3rd Gen to pick up at around 21 days or so. Once Igg antibodies start being formed (around 30 days or so)they become strong enough for the EIA to pick up at an average of 6 weeks. Once Igg's are produced they stick around until the very last stages of AIDS. That's why you occasionally hear about neg at that stage.

Now to sum it all up. 1st gen. uses Viral Lyzates as antigen. This detects only Igg antibodies and because it's not as pure of a process as the synthetic pepsides used in the 2nd Gen tests it tends to throw out more false posites because of cross reactions. As I mentioned the 2nd Gen uses synthetic pepsides to capture only Igg antibody, but because it is PURER than the former it can detect them about 5-7 days earlier. Now the 3rd Generation Recombitent Antigens which is even more pure and can catch both Igg (produced later during infection) and Igm which is the first antobody produced. Because of these 2 factors it can not only detect most infections by 21 days but has very few false negatives. WHERE DOES THIS PUT US? If you test negative between 5-6 months using 1st gen it's over 3 months using 2nd Gen and generally 2 months using 3rd. That's why countries that use only the 3rd are now lowering the window as low as 6 weeks. By the way it's fact that most US labs use 1st Gen w/ the exception of NYC (2nd Gen. in most cases. This information was given to me by a very reputable pathologist END OF STORY



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notanonymous
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Posts: 176
to anonymous, re: confidence intervals new
      #37785 - 08/02/02 05:08 PM

thanks for the info, i should have investigated the meaning of confidence interval. the link you provided is not very clear, IMO, this is a better one:

http://davidmlane.com/hyperstat/A29494.html

i would take this to mean that confidence interval is reflective of the percentage that would fall into that parameter. therefore stating that the confidence interval (95%) would fall between the parameter of 9-41 days, thus the average 25 days (9+41=50x.50=25). i would not see how 25 days could be used as an average time for seroconversion if almost all did not fall in this range. that would be an average of an average and i don't think that makes good math. same with the first generation studies, 34+55=89x.50=44.5(45 days). if you understand the meaning of confidence interval better than my interpretation, i would be greatful for your explanation because i still take it to be a true reflection of the window period, not a range of the average as you eluded to. thanks!



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Anonymous
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Re: to anonymous, re: confidence intervals new
      #37789 - 08/02/02 05:29 PM

Thanks for the site. Yes it does make it more clear from the site I refered to. It does in fact mean exactly what you state. That absolutely explains the 45 day average on first Gen tests that we see everywhere. that also explains where this 3 month window came from. Let's face it, how can all these experts including the CDC state that 3 months is conclusive if in fact they could't back it. Since I know most commercial labs in the USA use 1st Generation tests if it was common to test - at 3 months and then + at six there would be lots of noise. Further the State of NY concensus states that "As early as 1990 it was realized that almost all conversions happen by 3 months. I GUARANTEE YOU THAT IN 1990 ALMOST ALL LABS IN THE WORLD WERE USING 1st Gen tests.
Thanks Again.



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notanonymous
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Reged: 04/19/02
Posts: 176
Re: Regarding First vs. Third Generation new
      #37790 - 08/02/02 05:32 PM

thanks for your post. it brings some clarity but also more confusion. are you the person that wrote kull in oct. 01 about testing out 5 months to later discover first generation was being used by quest? i was tested through quest also through a third party anonymous phone service and they swore to me up and down that it was 3rd gen. i called quest a couple of times, once i was told they don't used "generation" terminology in the states, another time they told me it was 3rd generation type of viral lysate method!?!?!> yeah that makes a lot of sense. i told them viral lysate means first generation and they just didn't get it. i called the testing referral agency again, furious, and they still swore it was 3rd gen. and said they would call quest, they called me back and said quest stated it was 3rd gen but still viral lysate methology. jeez, these were lab techs saying this. they told me it was better because it was more sensitive. BS! the health dept i tested at had no clue what i was talking about, i called the head lab guy for the state health dept i live in and he had no clue about generations either, but low and behold, it was the same damn test from the same manufacturer using viral lysate. i just don't get it. i did a search under the "safe sex" forum on 'first generation' and clicked show all results (no omitting) and kull says at one point first is just as good at 3 months, but then on another post he changes his tune to first is as good at 6 months as third is at 3. there is also a post where someone wrote the head pathologist at quest and the guy stated that they use 3rd generation, but he doesn't say exclusively, yet it is implied. at any rate i am baffled that all facilities in every state do not use 3rd generation testing to cut down on anxiety as well as rate of transmission. so, if you read this, i tested neg at 12 weeks with 3rd generation and pcr rna. do you think i am ok?



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Anonymous
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Re: Regarding First vs. Third Generation new
      #37795 - 08/02/02 06:36 PM

Actually Kull says a 1st generation is as accurate at 23 weeks as a 1st is at 3 months. If you interpret 6 months as 26 weeks 23 weeks is a bit over 5 months. Regardless, I am not the guy that wrote in Oct. however I did test through Specialized Testing and Quest Labs at 8 weeks and yes I was told that they use 3rd Generation etc.. I believed them until I logged on the Quest Lab site and suspected they are affiliated with Home Access. I personally called and spoke to the same Pathologist that posted regarding Quest using 3rd Geneartion. Initially he told me that they did not go by generation terminology After I pressed him he called the manufacturer and verified with me that they do in fact use the Viral Lyzate method. Now he never told me that they use 1st Generation only that they use the kit that utilises Viral Lyzates. Granted the kit itsself is propably updated since it's initial approval date.

Now the question of why do most labs use 1st instead of 3rd. It truly is COST. The 3rd Generation is twice as expensive When you multiply Twice as expensive by tens of thousand of HIV tests that the average lab like Quest does a year that adds up to MILLIONS of $$$. Lastly how do they get away with it? that is why the CDC still uses the 3-6 month rule. Bottom line is that all of studies done re: the Window including 1st Generation show that 3 months is pretty conclusive regardless of the testing method. It's the same theory behind the 3 rd Gen. everyone knows that over 95% will test positive by 2 months but they throw the 3 months to make sure the outliers are caught. The same holds true with 1st Gen. they will propably catch 95%> by 3 or 4 months but they use the 6 month rule to ensure most are caught.

Now I say all this only after many hours of research and coorespondance with clinicians. also let's not forget that the health care system in the USA is generated by profit and hence the cost saving methods, to where in Socialized Medicine countries the labs could care less what it costs since their Government pays for it anyway. Why do you thing our health care system is such a mess w/ the HMO's all they want to do is save money at the expense of our health.

YES you are negative so don't worry but do pass on this info to others and for those who do not believe take the time to do the research yourself



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Chi
Member

Reged: 08/19/02
Posts: 35
please reply--true or false new
      #38432 - 08/19/02 01:44 AM

Orasure is a 3rd Gen test. True or False.

3rd Gen at 3 months is equivalent to 1st Gen at 5-6 months. True or False.

Please reply to chishu_2002@yahoo.com

God Bless.



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Chi
Member

Reged: 08/19/02
Posts: 35
Re: Regarding First vs. Third Generation new
      #38433 - 08/19/02 01:50 AM

Then can I jump for joy and say that i am negative ???? (tested negative at 90 and 96 days using orasure (3rd gen) test)

Sick with worry.





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