A Question regarding HIV Testing

Factual Questions
1

I grew up with a public school education, and from about 4th to 12th grade, I have been subjected to countless seminars, lectures, guest speakers and classes which focus specifically on HIV/AIDS and preventing it. The information I have recieved each year has been the same, essentially these matters:
HIV can be transmitted by needle sharing, sexual intercourse, and from mother to child during childbirth.
One can not be certain that his partner is free from HIV infection from his/her appearance, or based upon what he or she says, that the only way to be certain is to obtain results from an HIV test performed at least 6 months after infection has occurred.
Blood transfusions have not been a source of infection in the United States since 1986.

hearing this information repeatedly has provked me to question one thing: If HIV infection cannot be safely determined by the information provided by the individual nor by a blood test performed within 6 months of infection, how are blood banks able to insure that donated blood is free of HIV?

If the tests performed on donated blood are sufficient to determine if it is infected regardless of how long ago infection occurred, why must individuals who wish to get tested wait 6 months to recieve accurate results?

If a single test and interview is sufficient for the US medical community, why is it not sufficient for a sexually active couple?

I’ve asked this question of every individual I’ve known who claims to be knowledgeable on the subject, I’ve asked it in school, and I’ve never recieved a certain answer.

Anything anyone can tell me will be greatly appreciated, thanks.

2

I think our own JillGat can answer this one pretty handily. JILLL!

3

I’m not sure about the exact numbers, but the chance of a a mother with AIDS passing it to her children (through child birth) is actually fairly small. It’s something like 1 in 10 or 1 in 9. Although I’m not sure about the chances if she got the virus at the same time she concived the baby. That could make a difference.

Formerly known as Nec3f on the AOL SDMB

4

A Three month wait shows 98% of all HIV infections.

6 months, 99%

People who give blood must be interviewed first. This rules out a lot of infected people.

The AVERAGE period of time that an infected person will show
positive on the test is 25 days. This is an average, so not all people
will test positive by this point in time.

       The USUAL period of time that an infected person will show
       positive on the test is 3 months. This means that most (but not all)
       infected people will show positive on the test by this time.

       The MAXIMUM period of time that an infected person will show
       positive on the test is 6 months. By this point in time, more than 99%
       of infected persons will show positive on the test. This is as accurate
       as any test in medicine could ever be.

Try this graph of infectionous periods: http://www.thebody.com/sowadsky/images/timeline1.gif

5

I heard in the last few weeks that there is now an affordable medication that can be given to pregnant mothers, and greatly reduced the chance of an infant contracting HIV from its mother… JIL>?

Typer

6

I was under the impression that there are at least two types of AIDS tests. One screens for anit-bodies the other for the virus itself.

7

Presumably you meant exposure, not infection. Also the 6 months is only valid if your partner has a) abstained completely from sex, or b) been in a monogamous relationship with a partner who has also been monogamous. There is no getting around the fact that to enjoy worry-free unprotected sex with a partner requires a certain element of trust. Sometimes, unfortunately, that trust will be broken, and infection can result.

Blood banks CAN’T completely ensure that donated blood is free from HIV. They do test for antibodies. They do minimize situations in which anyone is coerced into donating blood, and in some situations (military blood drives where everyone is herded over to the blood bank) include the option for donors to indicate that their blood should not be used for donation, but still have their blood drawn.

All of these steps cannot completely exclude someone’s having HIV in their blood, but not having had enough time to make detectable levels of antibodies. The risk of acquiring HIV from a transfusion is low, but still not zero.

Because the need for blood is urgent, and because blood products have a limited shelf life.

No C&P - a couple of people asked about preventing mother baby transmission. Here’s a recent MSNBC story:
http://www.msnbc.com/news/289776.asp

Not mentioned in this is the fact that delivery by C-section can independently cut the risk by 1/3 - 1/2.

All of the tests in general use for screening are tests for antibodies, which take 1-6 months to become positive. Depending on the policies of individual lab facilities, most but not all + antibody tests are confirmed with a test for the virus itself. This test is also widely used to follow the course of HIV-disease progression, as viral count in the bloodstream goes up as the immune system and/or antiHIV drugs are failing to keep the virus in check.

Sue from El Paso
members.aol.com/majormd/index.html

8

What are the odds of contracting HIV though?My husband had aids,and we tried for 8 months to conceive(dont try this at home!)It was about 10 tries.I and my son are fine.What are the odds of that?

9

I’m glad someone brought up the Blood Bank discussion- I ALWAYS wondered why you have to indicate if they should use your blood or not, after being interviewed, filling out questionaires, etc. In NY anyway, you have to peel off a bar code indicating (confidentially) if they should use your blood. I never thought of someone like the military forcing people to give blood. I guess it’s a good safety precaution, then.

An optimist sees an opportunity in every calamity; A pessimist sees a calamity in every opportunity.

10

handy
Member posted 08-15-1999 11:18 AM "The MAXIMUM period of time that an infected person will show
positive on the test is 6 months. By this point in time, more than 99%
of infected persons will show positive on the test. This is as accurate
as any test in medicine could ever be. "

You mean there's only a 99% chance that those people in the graveyard are really dead? Aaah!

-Ryan
" ‘Ideas on Earth were badges of friendship or enmity. Their content did not matter.’ " -Kurt Vonnegut, * Breakfast of Champions *

11

Ryan, I didn’t write that part, I quoted it off some medical site.

Markxxx, they can look at your T-Cell count instead. A low T-Cell count takes no time at all to wait. I’ve been tested that way instead.

Also, for some reason, the amount of concern a person takes about getting HIV from sex is inversely proportional to how horny they are.

12

  1. I hope you mean that your husband is infected with HIV, and not that that he actually had AIDS (end-stage HIV-disease, where the virus is winning & the immune system is shutting down.) Unprotected intercourse with someone with AIDS is high risk for both parties. The uninfected partner stands a good chance of becoming infected. A mom who becomes pregnant & HIV-infected at or about the same time stands a much higher than normal chance of passing the infection on to her child. The partner with AIDS stands the risk of becoming infected with normal vaginal bacteria, which is not dangerous in itself, but by stimulating the immune system could lead to further explosion of HIV-carrying lymphocytes, & higher viral titers, and fewer uninfected lymphocytes. Acceleration of the progression of the AIDS is the major risk for the affected partner.
    (Sorry for the lecture, but confusion between HIV-infection & AIDS is common, & needs to be addressed)

  2. I don’t have good figures for the risk of acquiring HIV while trying to conceive. It depends on whether your husband’s HIV viral count was minimal (well-controlled with or without treatment) or high.

  3. Mom-to-baby transmission rates can be lowered by treating with anti-HIV drugs, by C-sections, and by not breast-feeding. I’ve seen with-treatment rates cited as low as 2-3%, which is fantastic news.

To clarify: the military DOESN’T force people to donate. It does place individuals in uncomfortable situations where they either have to reveal information their superiors have no business knowing or going along with the crowd. The “do not transfuse this unit” option allows tham to do so with a clear conscience.

Sue from El Paso
members.aol.com/majormd/index.html

13

The blood supply isn’t 100% safe, but the risk of contracting HIV from a blood transfusion are very, very low in this country. Almost all HIV transmissions from blood transfusions occurred before March of 1985, when HIV antibody testing became available for screening blood donations. Of course you are much more likely to die from whatever is causing you to need a transfusion anyway (or to contract another disease).

The HIV test you described is a test for antibodies to the virus. It’s actually a combination of two tests; the ELISA (or EIA), which is a very sensitive test and the Western Blot, which is more specific. This is a very good test for the presence of HIV, but you are right that there is a “window period” from immediately after infection until the antibodies are detectable. Six months is generally thought to be the outside parameter for when infected blood will show a positive test, but most infected people will test positive within three months. It is still possible for infected blood to make it into the blood supply, though it is rare now. The chance of contacting HIV from a blood transfusion in the US (risks may be higher in other countries) was estimated to be 1 in 450,000 to 1 in 660,000 transfusions in 1995. The risk of contracting Hepatitis B is about 1 in 63,000 per unit of blood transfused and about 1 in 100,000 for hepatitis C.

Blood is only accepted from volunteers in the US, and donors are questioned about risk factors for blood-borne disease (sexual practices, injection drug use, recent transfusions, etc). People are strongly discouraged from donating blood for the purposes of finding out their HIV status. The interview ends with the question, “Do you feel well and healthy today?” A simple “no” to even this question will disallow the blood from being drawn or used. Most people possibly infected with HIV are weeded out by this process. In the U.S., blood donors have one-fiftieth the positive HIV test results of the general population.

Besides the ELISA and Western Blot tests, donated blood is submitted to another laboratory test, the p24 antigen test. It detects the virus earlier than the antibody tests. It isn’t a reliable test for testing people to see if they are infected, but it is a good safeguard for blood donations when combined with the other tests. I am guessing that before long, blood donations will be screened with a PCR (polymerase chain reaction) or similar test which detects the virus even earlier still. Such tests are too expensive to use routinely now. At this point, though, from the donor interviews, antibody tests, and the p-24 antigen test, the chances of infected blood getting into the blood supply in the US are very, very small. But not impossible.
Jill

14

[[Markxxx, they can look at your T-Cell count instead. A low T-Cell count
takes no time at all to wait. I’ve been tested that way instead.]] Handy

What? I can’t imagine a doctor performing a t-cell count test for the purposes of identifying HIV. Many other disease conditions can cause a suppressed T-cell count, for one thing. I guess one might give you an HIV viral load test, but even that isn’t done routinely for the purposes of screening. Clarify here, Handy.

[[Also, for some reason, the amount of concern a person takes about
getting HIV from sex is inversely proportional to how horny they are.]]

Good point. Or how drunk they are.

[[What are the odds of contracting HIV though? My husband had aids, and we
tried for 8 months to conceive(dont try this at home!)It was about 10
tries.I and my son are fine.What are the odds of that?

  • Vanilla]]

MajorMD: [[1) I hope you mean that your husband is infected with HIV, and not that
that he actually had AIDS (end-stage HIV-disease, where the virus is
winning & the immune system is shutting down.) Unprotected intercourse
with someone with AIDS is high risk for both parties. The uninfected
partner stands a good chance of becoming infected.]]

As you pointed out elsewhere in your post, Sue, it is more important what the viral load is of the infected person - not whether they have an AIDS or simply an HIV positive diagnosis. Even persons with an AIDS diagnosis often have an undetectable viral load if they are on multi-drug therapies nowadays. There is some controversy about whether they are indeed not infectious, though it seems to make sense that they would be less so. HIV is not that easy a virus to contract. I have articles with estimates, but not with me at the moment. For vaginal intercourse, it’s something like one in a few hundred for the woman if the man is infected. And a man having vaginal sex with an infected woman is less likely to contract the virus. Of course it can also happen after one exposure, so I’m not saying go ahead and have sex 199 times, but be sure to use a condom that 200th time… Cecil has written about this some, but more information has come out since his column about it.

15

Jill, thank you very much for your information on this topic. I’ve heard the 1 in 450k statistic before in a few pieces of medical journalism a few years ago. It was this statistic which sparked my curiosity on the subject. Cecil’s claims (correct me if I’m wrong) that the chances of becoming infected with HIV through heterosexual sex with an individual who does not engage in high risk activities is approximately 1 in 12 million. These two statistics show the risk of infection from blood transfusion to be LESS than that of infection from heterosexual sex under those conditions.

I suppose my biggest concern is with the truthfulness of the information I’ve recieved in school. Every school which I have attended has essentially presented the position that having heterosexual sex, regardless of the partner puts you at risk for HIV infection, while recieving donated blood does not. I think it is clear that BOTH pose a risk, and in fact, the blood transfusion risk may be greater than that of heterosexual sex. Does anyone know why public school courses, lectures, and presentations take this seemingly backwards position?

16

This is off thread, but I hope someone can answer it nonetheless.
The medicos claim that HIV is a fragile virus, unable to survive on a toilet seat for example. Yet most blood is frozen. So why is blood donation a vector but not mosquitos? I am putting myself out on the limb here, but if you were to freeze the mosquito, it stands to reasom that the mosquito would die but the virus would not. Is there a “load” of virus you must recieve? What if you are bitten by 20 mosquitoes in one night

17

[[I suppose my biggest concern is with the truthfulness of the information I’ve recieved in school. Every school which I have attended has essentially presented the position that having heterosexual sex, regardless of the partner puts you at risk for HIV infection, while recieving donated blood does not. I think it is clear that BOTH pose a risk, and in fact, the blood transfusion risk may be greater than that of heterosexual sex. Does anyone know why public school courses, lectures, and presentations take this seemingly backwards position?]]

Uh yeah, I have a theory about that. Most school teachers want to scare youth out of having sex, so they focus on the potential risks rather than presenting a balanced picture. I’ve been asked to speak about AIDS in health classes to students who haven’t even been taught about puberty. I could go on about that.

I don’t think you can do a simple risk comparison between blood transfusions and heterosexual sex. There are too many variables involved. As for assigning risk to sexual activity, one major flaw I’ve seen in much HIV education is trying to assign risk to behaviors too simply: “anal sex is more dangerous than vaginal sex” or even to bodily fluids, as in “HIV is found in semen, vaginal secretions, and breast milk,” without adding the rest of the message. The rest of the message has to be that anal sex is only dangerous if your partner is infected (monogamous, uninfected partners - gay or straight - can have any kind of sex they want and cannot contract the virus from each other) and HIV is only found in those bodily fluids OF AN INFECTED PERSON. So to do a risk assessment, you must look at the potential for your sex partner being infected, as well as the kind of sex you have. If he or she had a negative HIV test last month, well that’s no guarantee that s/he isn’t still in the window period or wasn’t recently infected, but hey - it’s better than nothing. If a woman’s sex partner is a male who appears to be monogamous and she’s fairly certain that he hasn’t shot up drugs or had sex with men (and granted, one cannot ever know these things for sure), she’s probably at relatively low risk of acquiring HIV and should worry more about human papilloma virus, which can lead to cervical cancer.

I should add here that I have conducted personal in-depth interviews with over 250 persons living with AIDS in which I asked them questions about their sexual behavior. Some of them were healthy-looking, intelligent, attractive people who admitted to me that they lie to new sex partners about their HIV status in order to get them to have unprotected sex with them.

I know that others will be tempted to respond to this post, aghast that I am appearing to downplay the risk of acquiring HIV. I think we need to be honest and balanced in our information. Each person has to educate themselves and decide for themselves what level of risk they are willing to take.

Somebody asked me once why I wear a helmet when I rollerblade. I answered, “the chance of hitting my head is very slight, but the consequences if I do are great.”
Jill

18

Regarding mosquitos and HIV: http://www.cdc.gov/nchstp/hiv_aids/pubs/faq/faq32.htm
No. Can’t happen.

19

JillGat, there are a lot of diseases we don’t know about yet floating around in the blood supply.

Take Hepatitis C [So called ‘the new AIDs’], just recently discovered, do you think they retested the blood supply when they found a test for it?

20

Jill, what would you guess is the male/female ratio on this?:

‘I should add here that I have conducted personal in-depth interviews
with over 250 persons living with AIDS in which I asked them
questions about their sexual behavior. Some of them were
healthy-looking, intelligent, attractive people who admitted to me
that they lie to new sex partners about their HIV status in order to
get them to have unprotected sex with them.’

Makes me squeamish, but anyway, answer away.