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Doctor insights on: Positive Elisa Negative Western Blot

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What is difference between IgM and IgG for western blot for lyme. Positive for IgM but not IgG, what does that mean? Tks

What is difference between IgM and IgG for western blot for lyme. Positive for IgM but not IgG, what does that mean? Tks

Recent infection: Hi. IgM is present only with recent infection. After IgM levels fall away, IgG takes over for ongoing and recurrent exposure to antigen. (The antibodies in this picture are IgG's). I'm glad your doc was on the ball. She/he may have saved you a world of hurt by making the diagnosis promptly. Good luck! ...Read more

Elisa (Definition)

Enzyme-linked immunosorbent assay (elisa) is a test that uses antibodies and color change ...Read more


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When tested for hiv, how should a strongly positive ELISA test (index above 7) and a negative western blot be interpreted? What additional testing is required?

Likely negative: This is probably a negative test. If the results haven't changed in a month, then you're definitely not infected. If you don't want to wait that long, you could get a viral load test. An undetectable viral load would be highly reassuring, but i'd still repeat the serology. ...Read more

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Tested positive on IgG Elisa for hsv2. Then tested negative on western blot 2 years after last encounter. Which test to believe?

Tested positive on IgG Elisa for hsv2. Then tested negative on western blot 2 years after last encounter. Which test to believe?

Western blot: The ELISA screening test is sensitive with a smaller number of false negatives which makes a good screening test. That way fewer true positives are missed. The Western Blot is more specific meaning a smaller number of false positives. A specific test misses few true negatives. It is done for confirmation.

You can always repeat the tests in case of specimen mix-up (which I have seen happen before. ...Read more

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Tested positive on the ELISA test for hsv2, a month later tested negative via western blot 2 years after possible exposure. Which test to believe?

Tested positive on the ELISA test for hsv2, a month later tested negative via western blot 2 years after possible exposure. Which test to believe?

Both!: ELISA is very sensitive and sometimes gives a false positive. Interfering substances in serum can make the test look positive. On the other hand, Western Blot is very specific. It does not light up unless you really have antibodies to HSV. So, both tests were "right", but the Western blot indicates that you do not have the antibody to HSV and have not been exposed. ...Read more

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Does the western blot trump the elisa? Tested positive via ELISA IgG for hsv2, but later tested negative via western blot. No symptoms. Do I have hsv2?

Does the western blot trump the elisa? Tested positive via ELISA IgG for hsv2, but later tested negative via western blot. No symptoms. Do I have hsv2?

Western blot more: Specific, ELISA more sensitive. One positive ELISA and one negative Western blot says that you do not have enough antibodies to HSV 2 for confirmation of diagnosis. It may be prudent to repeat the tests in 3-4 months to make sure that negative Western blot was not due to incomplete/early immune response. ...Read more

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Tested false positive ELISA HIV test last month. Negative ifa and western blot and naat. 2 negative oraquick all 1 1/2 year post exposure. Hiv?

Tested false positive ELISA HIV test last month. Negative ifa and western blot and naat. 2 negative oraquick all 1 1/2 year post exposure. Hiv?

Negative: If nat was negative at 6 months after exposure you not likely to have hiv. Given all the negative test results, you should not worry about the one apparently false positive. ...Read more

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2009- ELISA HIV test- positive, western blot- neg. 2010-oraquick negative. 2014- elisa-indeterminate wb- neg. Low risk for hiv. Could I have lupus?

Not a test for lupus: The HIV test is not a test for lupus. What's clear is that you don't have hiv. You'll never know why your elisa was positive and then indeterminate, and it's not worth investigating. False positive elisas are not uncommon; that's why they have to be confirmed with western blot. ...Read more

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False positive ELISA HIV test. Neg western blot, neg ifa &naat. I've had 2 neg oraquick home test. Could I be an elite controller? Or already have aids?

False positive ELISA HIV test. Neg western blot, neg ifa &naat. I've had 2 neg oraquick home test. Could I be an elite controller? Or already have aids?

No: Western blot is fairly definitive. You have 2 negative home tests and you are quite stressed about your testing:
her's an idea: use condoms: protect yourself (and others) at all times. ...Read more

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1 exposure on Jan 4th, 2014.Tested NEGATIVE on all 4th Gen. ELISA and HbsAg after 3 Months and 5 Months. Also, tested NEGATIVE after 6 months on ELISA and WESTERN BLOT. Do I need any more test? Please help

Too complicated: This question is too complicated for a short online question/answer format. The professional ordering these tests should be the one to tell you what if any further testing is needed. ...Read more

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Tested negative on 3 week ELISA blood test, but still scare and if I do western blot isn't it 100% accurate?

Repeat ELISA: If you must know, you can get a pcr (polymerase chain reaction) for the HIV virus (this is what you're worried about, correct?) I'm sorry you had a mishap -- trusting you'll return to a safety-focused lifestyle, and I'm glad you're brave enough to test tested. Wishing you the best. ...Read more

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With lyme disease you have ELISA and western blot but what if you tested ELISA negative is Lyme disease impossible? Or wise to do western blot?

Lyme blood test: In early Lyme Disease Elisa can be negative. No use testing Western Blot if Elisa is negative. Follow patient clinically and if symptoms of Lyme disease occur re-test Elisa. ...Read more

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Should I get an ELISA or western blot test if my hiv1&2 rapid tests come out negative? Hiv rapid is reliable?

PCR: The reason I would urge you to get the pricey pcr is that is is clear that you are worried, and it is costing you emotional energy. Pcr is the gold standard and will give you the right answer before either of the others. I hope things turn out well, but having HIV is no longer a death sentence. Good luck, live and love responsibly, and keep taking a proactive approach to your health. ...Read more

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With todays ultra sensitive modern ELISA tests, what use is the western blot for hiv? A few months ago I received a weakly reactive cmia HIV ag/ab test, a 4th generation HIV combo test, and this was followed by a negative western blot and a negative p24 t

With todays ultra sensitive modern ELISA tests, what use is the western blot for hiv? A few months ago I received a weakly reactive cmia HIV ag/ab test, a 4th generation HIV combo test, and this was followed by a negative western blot and a negative p24 t

False-positives: Screening tests are designed to be highly sensitive so they don't miss anyone with the disease. However, they can be so sensitive that they occasionally give a false-positive result. That is, the test appears positive for someone without the disease. The western blot, being time consuming and extra cost, is only used to make sure a positive is really a positive. Talk with your doc for more info. ...Read more

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2 false pos ELISA HIV tests, all 1 1/2 years post exposure. Neg western blot, ifa, naat and 2 neg oraquick home tests. What is my HIV status? Help!

2 false pos ELISA HIV tests, all 1 1/2 years post exposure. Neg western blot, ifa, naat and 2 neg oraquick home tests. What is my HIV status? Help!

Likely negative: There is typically a "window" of 3-6 months after exposure where you could be HIV positive but test negative. Since you didn't get your testing until well after that, i'd say the confirmatory tests (western blot, ifa) are what you should go by. The elisa is very sensitive and can have false positives- that's why we rely on the confirmatory tests. I would consider your status to be negative. ...Read more

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Wht cause a false pos ELISA HIV test with neg naat and western blot? 2 neg oral fluid rapid results. After 1 year exposur. Ihave autoimmune hypotyroid

No answer: Please. How many times are you going to ask the same question. There is no right answer here. Your body has something triggering the simple HIV antibody test to be positive. It is not HIV causing this symptom. In the future you should avoid these tests and get the better test. You have been given this answer numerous times. It is time to move on. ...Read more

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False pos ELISA HIV tests, neg naat viral load test, neg western blot, ifa and oraquicks neg too. All 15 months post risk event. What should I do?

False pos ELISA HIV tests, neg naat viral load test, neg western blot, ifa and oraquicks neg too. All 15 months post risk event. What should I do?

Be grateful, man!: You've been obsessing about this too long. Sit down and talk with your physician about fears. If you'll forgive my frankness, talk with him/her and some wise adults (maybe even dad) about your emerging sexuality and how you've explored. By your age, we've all made mistakes. Embrace being a man, decide how you want love to be for you, and cherish adult love while resolving to be safe ; kind. ...Read more

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Hi doctor. Is eli a more developed ELISA test for HIV? And is ecl a western blot test? (if yes for ecl) I had a negative p24 at 3 month am I negative

Hi doctor. Is eli a more developed ELISA test for HIV? And is ecl a western blot test? (if yes for ecl) I had a negative p24 at 3 month am I negative

Not Best Focus-Vague: Acronyms are too vague & not clear. However, the bigger issue is attributing too much significance to any specific test, all of which have issues of both false positives & negatives, never perfect. The larger issues are both probability, look up "bayes' theorem" & the many variables/complexity of exposure combined with individual responses over time. Before >6 months, reliability of HIV tests low. ...Read more

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My brother had a positive ELISA test for HIV followed by an indeterminate western blot. His viral load detected no virus. How confident should I be?

Pretty confident: It sounds like's he's negative and just happens to have an indeterminate wb. This happens sometimes, for reasons that are never entirely explained. However, I would recommend that he get the elisa and western blot retested one month after the first. If there has been no progression of the WB (addition of new bands), then he's definitely negative. ...Read more

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How reliable is a HIV ELISA test vs a western blot?

HIV testing: Elisa assay is quite sensitive (will detect antibodies best) but the western blot is more specific and confirm the results of the elisa if it was positive, as being either truly positive or false-positive. There are several other circumstances in which conditions other than HIV will produce a positive elisa assay. If there are symptoms and too early for antibody test, then PCR for RNA is best. ...Read more

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Is an HIV ELISA test always done with an western blot test?

No: In general, the elisa is done first, and the lab then does a western blot if the elisa is positive. However, it is possible to order just the western blot, in which case the elisa usually isn't done. ...Read more

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How and where do I get/take the western blot HSV-2 test? All I can find is the ELISA HSV test.

How and where do I get/take the western blot HSV-2 test? All I can find is the ELISA HSV test.

U of Washington: HSV Western blot is done almost exclusively at the University of Washington in Seattle, where the test was researched and developed. It's generally the best test to confirm an uncertain HSV blood test result, but often other tests (e.g. inhibition, immunoblot, BiokitUSA) are adequate and available at routine labs. If your doc recommends WB, s/he can contact UW lab for a test kit and instructions. ...Read more

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So there are no tests other than ELISA and western blot that would detect HIV if a person is sure of an encounter with an hiv+ person?

Repeat testing: It may take up to 6mos after an exposure to HIV for the ELISA & western blots to turn positive. If you were exposed to HIV & had negative tests, it is recommended that you get retested in 6 months. If positive, your doctor will perform more detailed studies, like viral load & CD4 counts. Not all exposures result in HIV infection, however you should use precautions to protect yourself & others. ...Read more

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2 + elisa, 1 -western blot, 1 -ifa and -natt, 2 -oraquick hometest all 1 year after exposure. Is HIV my problem?

HIV testing: No, but you no longer should ever do the HIV antibody test. If your doctors are not giving you the HIV pcr test then you may need to change who is testing you if you are worried about HIV exposure. ...Read more