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Final word on Herpes test Accuracy
Dr. Hook/HHH,
Thank you for running the forum. It is a blessing. I'll get to it. I am trying to get a grip on the accuracy of the IGG blood tests (herpeselect particularly), and the Western Blot.
It has been discussed on this forum a few times, as best I can tell, as well as on the Herpes forum. My perception is the three of you seem to vary somewhat in your opinions. My understanding that all of you are confident that there is sometimes a high rate of false positives, which can be sorted out by a University of Washington Western Blot in nearly all cases.
Also, if you want the most accurate test, you should wait 16 weeks post exposure and in some outlying cases, wait 6 months.
The false negatives seem to be a point of contention from what I observe though. Terri Warren seems to be really confident in Western Blots, and can only point to a couple handful of cases in her clinic where there were definite false negatives if proper wait times were followed. But I have also read that 'seroconversion' can be as low as 90% in other responses on the STD forum... To me, as an individual, 1 out of 10 missed infections seems room for worry/doubt. I was actually considering emailing the UW WB lab for direct numbers but I was hoping on your definitive opinion(s) as well. I know the WB is the gold standard an its been around since the 80s? Do we really know it's false negative rate/accuracy?
Thank you for running the forum. It is a blessing. I'll get to it. I am trying to get a grip on the accuracy of the IGG blood tests (herpeselect particularly), and the Western Blot.
It has been discussed on this forum a few times, as best I can tell, as well as on the Herpes forum. My perception is the three of you seem to vary somewhat in your opinions. My understanding that all of you are confident that there is sometimes a high rate of false positives, which can be sorted out by a University of Washington Western Blot in nearly all cases.
Also, if you want the most accurate test, you should wait 16 weeks post exposure and in some outlying cases, wait 6 months.
The false negatives seem to be a point of contention from what I observe though. Terri Warren seems to be really confident in Western Blots, and can only point to a couple handful of cases in her clinic where there were definite false negatives if proper wait times were followed. But I have also read that 'seroconversion' can be as low as 90% in other responses on the STD forum... To me, as an individual, 1 out of 10 missed infections seems room for worry/doubt. I was actually considering emailing the UW WB lab for direct numbers but I was hoping on your definitive opinion(s) as well. I know the WB is the gold standard an its been around since the 80s? Do we really know it's false negative rate/accuracy?
MEDICAL PROFESSIONAL
Already answered as best I can. See above: "For HSV-2, which is the important one from a genital herpes standpoint, it's far lower -- probably only 2-3% for testing done 4+ months after the last possible exposure." As this suggests, I agree the older 5-10% estimate was too high.
The available data do not allow a more precise reply, so that will have to end this thread.
The available data do not allow a more precise reply, so that will have to end this thread.
MEDICAL PROFESSIONAL
You haven't overstepped. Thanks for correctly summarizing the current state of the science of HSV-2 blood tests.
I don't have any other comments. That will end this thread. Take care and stay safe.
I don't have any other comments. That will end this thread. Take care and stay safe.
Thank you for the confirmations and information Dr. HHH. I wanted to follow up on this info... I read a bit more on the forum, and it appears lots of folks agonize over this. Terri Warren's page just had a similar post about it all this week! In fact a quick search revealed many posts about it... are you good Doctors tired of fielding the same questions yet? Forgive me if I post a couple links to other conversations about the issue, but maybe I can help other readers who have the same doubts as I have get a better, centralized understanding...
Terri responded really confidently here a few years ago, saying she's only had 9 patients in 30 years ever to not seroconvert for HSV2... which I imagine is a really, really small number for her clinic...
http://www.medhelp.org/posts/Herpes/prior-HSV-1-effect-my-western-blot-for-HSV2/show/1651017
I gathered from other forum posts, that it is not appreciated when old questions are pulled up out of context, but I thought this one of yours was relevant from 2010, where you stated false negative HSV-2 results may range from 5-10% (but you seemed to lean towards 5%).
http://www.medhelp.org/posts/STDs/Symptoms-of-Herpes-with-no-Antibodies/show/1362775
I gather since this is from 2010, your current opinion has more confidence in the tests... and the 2-3% is probably more likely? Not trying to split hairs, just get a solid sense of things.
I actually e-mailed Dr. Wald on the subject, since I know she (like you) is a great authority on the matter. She largely echoed your position. She neglected to offer any hard numbers, but the sense I got from my conversation with her (she was awesome to be kind enough to respond btw) was that a 6 month negative WB pretty much trumps everything, even the sometimes overly sensitive herpeselect. Since the WB is the gold standard, there is no comparator to really get a grasp on the false negative numbers, but she has not really seen any cases of clinically evident infection that did not eventually have a positive or otherwise suggestive WB result. I know she works in a lab setting and not a clinical setting, so her view may be different than yours or Terri's. Still, I found her response hopeful. I almost get the impression the 2-5% 'range' that seems to be the pattern may even be a 'safe' estimate when the 'reality' of false negatives may be even more rare than that.
Sorry if this was overload, Dr. Handsfield. You have given "blog-like" responses to the touchy subject of HPV in the past that I have personally benefited from, and I know countless others have as well. I know this topic gets talked about often, and thought maybe a 'collected' response like this may also help folks in a similar fashion. Forgive me if I have overstepped my bounds.
Terri responded really confidently here a few years ago, saying she's only had 9 patients in 30 years ever to not seroconvert for HSV2... which I imagine is a really, really small number for her clinic...
http://www.medhelp.org/posts/Herpes/prior-HSV-1-effect-my-western-blot-for-HSV2/show/1651017
I gathered from other forum posts, that it is not appreciated when old questions are pulled up out of context, but I thought this one of yours was relevant from 2010, where you stated false negative HSV-2 results may range from 5-10% (but you seemed to lean towards 5%).
http://www.medhelp.org/posts/STDs/Symptoms-of-Herpes-with-no-Antibodies/show/1362775
I gather since this is from 2010, your current opinion has more confidence in the tests... and the 2-3% is probably more likely? Not trying to split hairs, just get a solid sense of things.
I actually e-mailed Dr. Wald on the subject, since I know she (like you) is a great authority on the matter. She largely echoed your position. She neglected to offer any hard numbers, but the sense I got from my conversation with her (she was awesome to be kind enough to respond btw) was that a 6 month negative WB pretty much trumps everything, even the sometimes overly sensitive herpeselect. Since the WB is the gold standard, there is no comparator to really get a grasp on the false negative numbers, but she has not really seen any cases of clinically evident infection that did not eventually have a positive or otherwise suggestive WB result. I know she works in a lab setting and not a clinical setting, so her view may be different than yours or Terri's. Still, I found her response hopeful. I almost get the impression the 2-5% 'range' that seems to be the pattern may even be a 'safe' estimate when the 'reality' of false negatives may be even more rare than that.
Sorry if this was overload, Dr. Handsfield. You have given "blog-like" responses to the touchy subject of HPV in the past that I have personally benefited from, and I know countless others have as well. I know this topic gets talked about often, and thought maybe a 'collected' response like this may also help folks in a similar fashion. Forgive me if I have overstepped my bounds.
MEDICAL PROFESSIONAL
Welcome to the forum. Thanks for your question.
Your analysis of the false positive problem and the role of Western blot confirmatory testing, and its timing, is accurate. I don't think I could have summarized it better myself.
The problem with test sensitivity -- the ability of the available test to pick up known HSV infections and how quickly testing becomes positive -- is that the data are less clear. That in turn results in sometimes conflicting advice as equally qualified experts interpret the available data somewhat differently.
Still, your research may have missed a couple of important points. First, the problem of false negatives is much greater for HSV-1 than HSV-2. Some data suggest that up to 10-15% of people with HSV-1 may have negative IgG test results. For HSV-2, which is the important one from a genital herpes standpoint, it's far lower -- probably only 2-3% for testing done 4+ months after the last possible exposure.
WB actually may be less sensitive (i.e. miss more infected people) than IgG testing, at least for HSV-2. That's one reason it isn't generally recommended as an initial test; it's main role is to confirm weakly positive or ohter atypical or unexpected results by IgG. In other words, WB is rarely recommended when IgG is negative, especially for HSV-2. There are exceptions, but that's the general rule.
A very important consideration is that HSV antibody results are never interpreted (or should not be) in a vacuum -- i.e. by themselves, independent of other factors. In other words, the prior risk of herpes (e.g. nature and number of sexual partnerships), suspicious symptoms or not, sex with known infected versus unknown partners, and so on also can and do influence test result interpretation. If someone is statistically at low risk, has symptoms not typical for herpes, etc, a negative blood test can be considered extremely reliable in being confident HSV is absent.
I hope this has helped a bit. Best wishes-- HHH, MD
Your analysis of the false positive problem and the role of Western blot confirmatory testing, and its timing, is accurate. I don't think I could have summarized it better myself.
The problem with test sensitivity -- the ability of the available test to pick up known HSV infections and how quickly testing becomes positive -- is that the data are less clear. That in turn results in sometimes conflicting advice as equally qualified experts interpret the available data somewhat differently.
Still, your research may have missed a couple of important points. First, the problem of false negatives is much greater for HSV-1 than HSV-2. Some data suggest that up to 10-15% of people with HSV-1 may have negative IgG test results. For HSV-2, which is the important one from a genital herpes standpoint, it's far lower -- probably only 2-3% for testing done 4+ months after the last possible exposure.
WB actually may be less sensitive (i.e. miss more infected people) than IgG testing, at least for HSV-2. That's one reason it isn't generally recommended as an initial test; it's main role is to confirm weakly positive or ohter atypical or unexpected results by IgG. In other words, WB is rarely recommended when IgG is negative, especially for HSV-2. There are exceptions, but that's the general rule.
A very important consideration is that HSV antibody results are never interpreted (or should not be) in a vacuum -- i.e. by themselves, independent of other factors. In other words, the prior risk of herpes (e.g. nature and number of sexual partnerships), suspicious symptoms or not, sex with known infected versus unknown partners, and so on also can and do influence test result interpretation. If someone is statistically at low risk, has symptoms not typical for herpes, etc, a negative blood test can be considered extremely reliable in being confident HSV is absent.
I hope this has helped a bit. Best wishes-- HHH, MD
You are reading content posted in the STDs Forum
Herpes spreads by oral, vaginal and anal sex.
Herpes sores blister, then burst, scab and heal.
STIs are the most common cause of genital sores.
Millions of people are diagnosed with STDs in the U.S. each year.
STDs can't be transmitted by casual contact, like hugging or touching.
Syphilis is an STD that is transmitted by oral, genital and anal sex.
