There is a lot of misinformation about herpes, both among health providers and the general public. When I lecture at a medical conferences about herpes I hear, “I didn’t know that,” all the time. I know people want more information, because I posted a piece in 2011 on the difference between type 1 and type 2 last year and it has over 48,000 hits and counting.
One big area of misunderstanding is blood testing and herpes infections. Blood testing means looking for antibodies. The immune system produces antibodies in response to an infection, and so the presence of antibodies means that at some point there was an infection somewhere with herpes. Now keep in mind that most people with herpes are unaware they have been infected because most people don’t get recurrent cold sores on their lips or genitals, most people have a silent infection and simply periodically shed the virus.
What you need to know about blood testing before you have it:
1) There is only one reliable and commercially available type of blood test for herpes antibodies called a Type Specific IgG. This test can reliably distinguish between herpes 1 and herpes 2 antibodies. There are labs that will run tests that are not type specific, but these are essentially useless. It is unfortunately not illegal to offer a useless test and some providers just don’t know the difference and may just tick off the first box for “herpes” that they see. The University of Washington (the mecca of herpes research) also offers a Western Blot test for herpes antibodies. This is the gold standard, but only performed at the University of Washington. The American Social Health Association has a great guide to the brand names of the reliable tests. If it’s not one of these tests, don’t get it. You may have to ask your health provider to check, because they might not know.
2) Blood tests take 3-6 months to turn positive after exposure because it takes 3-6 months for your body to make IgG antibodies in response to an infection.
3) There is no blood test that can tell you immediate exposure/recent infection. Some less than scrupulous labs and providers might tell you to get an IgM test. IgM antibodies are produced very soon after an infection. If your provider offers an IgM test, get up and leave because they do not know anything about herpes or testing. IgM tests for herpes are highly unreliable for the diagnosis of herpes virus infections and should never be ordered (the FDA doesn’t prevent companies from offering bad tests, just doesn’t approve them).
4) A positive IgG to herpes does not tell you when you acquired the infection, just that at some point you did. Often people are exposed to the virus but don’t have their first outbreak for months or even years later. A positive herpes IgG test only tells you that at some point in time you acquired the herpes virus (1 or 2 or both depending on your results). Many people pick up herpes 1 as a child. This is innocent exposure from sharing slobbery toys in daycare or kisses from someone who is shedding the virus but has no active cold sore.
5) A positive IgG also doesn’t tell you where you have the virus. This is very important, because 50% of new genital lesions are due to herpes type. Basically, if you test positive for herpes type 1 and negative for 2 that does not mean you don’t have genital herpes. You could be carrying herpes type 1 in the mouth, the genitals, or in both places. Recurrent sores on the mouth are more likely to be type 1 and recurrent sores on the genitals are more likely to be type 2, but that’s more likely not always. If you only test positive for type 2, that could have been an oral infection.
6) How will the test change your behavior? Will it make you be more careful sexually? Well, you should be more careful anyway. Will you only date people who are negative for both herpes 1 and 2? (remember, herpes type 1 can cause genital infections). If that’s the case, will you have a sexually chaste relationship, even abstaining from kissing, for 6 months to be rested to see if you are still negative? What if you are just positive for herpes 1, because that doesn’t rule out genital herpes? If you are positive for herpes 2 and have never had a genital outbreak, it is possible that the herpes 2 you have is an oral infection and not genital.
8) The CDC does NOT recommend routine blood testing for herpes . There is no evidence that testing changes sexual behavior (see above). And the mental gymnastics about how to manage the test results are just too complex (see above).
The best reason for blood testing is when there is a specific question or diagnostic dilemma. Three scenarios might be…
1) A person has a recurrent genital ulcer that seems atypical for herpes. As part of the work up, blood tests for herpes may be ordered and, if negative, repeated in 4-6 months. This is part of a medical work up of a specific problem.
2) A person with known genital herpes who wishes to reduce the risk of transmitting the infection to their sexual partner. Taking antiviral medications can reduce this risk by about 50%. However, if the partner is positive for the same herpes virus, then the medications might not be needed. This scenario is really partner testing.
3) There is also an argument that goes back and forth about testing during pregnancy as a new infection during pregnancy close to delivery can be very dangerous to the baby. This would require weeks of posts to address appropriately, but suffice it to say that The American College of OB/GYN (ACOG) does not recommend routine blood testing for herpes during pregnancy.
Before you decide to get a blood test for herpes, get informed. Herpes blood tests are expensive and can’t tell you when you caught herpes or even if the virus in your mouth or on your genitals. What if you just want to be “Screened for everything?” Herpes blood tests are not screening tests, but tests that should be used to answer a specific problem. If your question is, “Do I have genital herpes,” that answer can’t be answered reliably with a blood test.
Remember, this post is not direct medical advice
Now I understand how the lab managed to run one of those bogus antibody tests for malaria on me! (The doc ordered the right thing, they didn’t offer it and substituted the closest thing they had. I couldn’t understand why it was even offered.)
Posted by Loren Pechtel | January 19, 2013, 11:46 amExcellent! Thank you.
Posted by Ann Friedmann | January 19, 2013, 12:47 pmNow I’m super confused! What about viral culture obtained from a new oral or genital lesion? Those should be reliable, because then you are getting an actual sample of the virus. Right?
Posted by Melissa | January 19, 2013, 6:36 pmI guess I talked myself to the answer!
Posted by Melissa | January 19, 2013, 6:36 pmA test from the lesion is a different thing than a blood test. I will post on lesion tests later this week. A viral culture is not the necessarily the “best” test for a lesion. Stay tuned.
Posted by Dr. Jen Gunter | January 19, 2013, 6:40 pmDr Jen , I would like to ask u is it normal to have re accruing ob,s every week from November 2012 to may 2013 on weekly basis ? I was diagnosed positive in 2009 through a swab and 3 weeks ago swab was taken again and it came back negative , I am so confused , Cld this be something else ? What else Cld this possibly be ?
Posted by Hasan | May 11, 2013, 9:35 ami to have had this virus for 20 years but have been told it is shingles and have been treated as such and i to am now asking myself is it something else
Posted by ann corby | May 14, 2013, 2:34 amWhen the results come back “equivocal” (four months out from “last contact”), what is the ideal amount of time to wait before retesting?
Posted by Some Random Female | January 20, 2013, 5:58 pmIt takes up to 6 months for IgG to develop
Posted by Dr. Jen Gunter | January 21, 2013, 7:22 amMy GYN offered the IgG to me in addition to other STI testing after my divorce about three years ago. I really wish I’d never had the test; it showed me as positive for HSV 2 and then I was left trying to figure out just how long I’ve been carrying it around. I did tell my ex-husband, just in case, but I wasn’t prepared to track down all my past sex partners to let them know.
Like the people in the NEJM study you linked to, I appear to be asymptomatic. There is really poor information to help one understand what “symptoms” are, though. As noted in the study, people need to be very clearly educated on how to tell they are experiencing symptoms of HSV or if it’s something else. I’m frequently questioning what the heck is going on now that I know I have the virus: Is that little bump an ingrown hair from my last waxing, or is it a lesion? Is that a “tingly” feeling in my upper thigh? Is that a pimple on my rear or something else? It’s really sort of maddening.
Question: In your original article that you linked, you mentioned that HSV is transmitted via bodily fluids. In the reading I was doing on the CDC and U of Washington sites, I thought it noted that it is transmitted skin to skin. Which is correct?
My current partner was informed and he tested negative. He doesn’t care about the HSV, and since we’re in a long-term, monogamous and committed relationship and all other tests came back fine we don’t take any special precautions. So being HSV positive doesn’t mean that one must give up on all sexual relationships, although it does present a lot of complications. I still worry that I will inadvertently infect him, especially since I have no way of knowing when I could be shedding.
Posted by lanalee | January 21, 2013, 8:07 pmLanalee…..I feel the same way. I wish I would never have been tested because now I am really confused. I only tested because I heard people can carry herpes for years and never know it. I have never had any symptoms…and I tested high for the antibodies.
Posted by Gina | May 13, 2013, 4:19 pmI am really conflicted about getting the test. in 2007 I had a strange symptom, like a crater on the shaft of my penis. it didn’t hurt and it cleared up in a week or so and has never returned. As my girlfriend ay the time (we are still together) was a virgin I didn’t think it was anything to worry about. I was also working abroad in a country with a poor medical system so didn’t go to a doctor.
However, in 2011 I read an article about herpes and I’m now terrified that’s what it was. I haven’t had sex with my girlfriend since and I’m terrified to in case I give it to her. I haven’t told her because I am terrified that she’ll leave me and I also don’t want to scare her for nothing because I have since spoken to health professionals who have told me there is no way to know what it was, and that based on my sexual history they think it’s unlikely to be herpes, hut not impossible.
We are both in our early 30s and she is hinting about marriage and kids, but how can I consider that if there is a risk I could infect her with something? This is ruining my life. I would give anything for a test that could identify if I have a genital infection.
Posted by Conflicted | February 24, 2013, 1:27 pmThis is so helpful and I am so grateful to you! I am amazed at the lack of information about herpes and even worse, the amount of misinformation given about herpes by doctors. It must be true, the more you know, the more you know you don’t know! Still waiting for your viral culture post please and thank you……
Posted by grateful | March 28, 2013, 6:59 amA professional lab testing is much needed for accurate blood testing without any stress and Any Lab Test Now offer a best blood lab testing in Waco TX. Thanks for giving this information. Great post!
Posted by aldengarcia | March 31, 2013, 9:51 pmYou mentioned that igg non specific tests are useless. What if someone thought they had been exposed to either type of virus, had this test done at the 6 month mark and received negative results. Would that suggest that the person has infact had no infection of either type or would there still be a risk of the person not producing enough antibodies for that test to pick up? I would think a non specific test would show a false positive before a false negative, is that correct?
Posted by john | April 12, 2013, 2:41 pmDr. Jen,
I have been married for two years. I heard rumors that my husband had herpes, but he assured me the rumors were false. I went and got tested anyway, and it came back positive. He immediately went and got tested, and it came back negative. The VA doctor wrote up a paper for him that stated that he “showed no immunologic response to herpes”. I also heard them on the phone tell him that the herpes test was negative. I haven’t been with anyone other than him, so how could this be?
Posted by Mattison | April 23, 2013, 12:58 pmWere you negative for type 1 or 2? You could have gotten HSV 1 (cold sore) as a kid. What Dr Jen has been saying is that there are test that don’t tell you which HSV type which makes the test worthless.
Posted by Tommy Gekk | May 9, 2013, 8:20 amA 2 week old newborn tested weak positive igm but negative igg and all other blood work, spinal tap fluid, swab tests, etc tested negative for herpes. Mother, father and brother were all tested and results were negative igm and igg. Newborn did not show signs of herpes rash but pediatrician asked for bloodwork to be done and parents complied. Hospital refused to allow opportunity for newborn to be retested. Is it possible the original test was a false positive? And if the original results were correct should newborn show signs of a positive igg in the future if tests were redone?
Posted by Wendy | April 25, 2013, 7:16 amThere is no IgM blood test, so the scenario that you give is not biologically possible to explain.
However, let’s take a hypothetical case where a baby is born and within a few days is suspected of having herpes encephalitis
Infants get herpes encephalitis at birth (acquire HSV at birth) when the mother is having her first outbreak as these often occur without symptoms. Meaning she contracted HSV, is shedding the virus, but has no active lesions. This is the most likely scenario for neonatal herpes as viral shedding without lesions is very common. The mother then does not yet have protective IgG antibodies and neither does her newborn as they take 2-3 months to produce. IgG antibodies do cross the umbilical cord, so that is why primary herpes is much more devastating for a baby exposed at birth than secondary herpes where the mother has IgG antibodies to pass on to her infant.
The baby would be expected to be negative for IgG by serology for herpes as would the mother (however, re-testing at 1,2,3 and 6 months should produce a seroconversion for both) is the lesions the baby had were herpes (of herpes were the cause of the encephalitis). The diagnosis of herpes in the mother and the baby would be made by PCR. The diagnosis of herpes in the infant would be confirmed by PCR either from lesions or from the spinal fluid and if it were close enough to delivery, the mother could have a vaginal swab done for herpes PCR. However, by 2 weeks there is a chance this too could be negative and so re-testing the mother for antibodies to see if she seroconverts would ultimately prove where the herpes came from.
In this scenario if the baby tests negative for herpes by PCR then that is unlikely to be the cause of the condition.
Posted by Dr. Jen Gunter | April 28, 2013, 11:16 amThank you for the quick response. The baby tested negative for herpes on the PCR using both spinal fluid and blood but the doctors forced parents to keep newborn in hospital and treat as if newborn had herpes/HSV 1. Hospital would not discharge newborn unless parents complied with the antibiotic treatments. Mother has tested negative for herpes virus as well.
Is it possible the original igm test was incorrect? Is there a false positive rate on that test is for a newborn? Pediatrician informed parents the positive igm was a result of bloodwork that he ordered on newborn.
Posted by Wendy | April 28, 2013, 12:22 pmThere is no IgM test that is reliable, so in this hypothetical situation the IgM means nothing. I can’t imagine designing treatment around a unreliable test.
PCR is pretty much the gold standard for diagnosis, so….
Posted by Dr. Jen Gunter | April 28, 2013, 2:00 pmThank you so much. You were very helpful.
Posted by Wendy | April 28, 2013, 4:08 pmKeep in mind my all comments are all based on a hypothetical scenario and not medical advice.
There are a myriad of other variables to consider not presented in your hypothetical case. For example, the accuracy of the lab doing the PCR.
Posted by Dr. Jen Gunter | April 28, 2013, 4:30 pmHi Jen,
I am about to do a PCR blood test for Herpes for experimental reasons. I am positive for HSV1 and 2 according to the antibody test and also had lesion swabbed to confirm HSV2.
The biggest lab locally does not do the PCR blood tests as they state that viral cultures are not present in the blood, only antibodies and they just do not feel they would be doing the right thing by offering this service.
I red somewhere that there is some PCR DNA test that looks for presence of a virus waste products in the blood and that is somehow different from and ordinary PCR test. What is your opinion on that?
Another question, would the PCR blood test for viral culture show the positive results straight away after you’ve been infected.
Posted by Poisonous | May 7, 2013, 1:38 amI had an outbreak of what was swabbed & PCR came back showing HSV 2. I have been a faithful wife to my husband of 15 years. It’s been horrendous for our marriage & he has had 2 blood tests, both negative. I hate him & hate myself. My doctor shiwed me stats of HSV in Australia. I told him I didn’t give a shit about statistics, i’ve slept with 2 men in my life, both virgins- Dr asked if I had a penchant for virgins. Same Dr told my husband I was obviously cheating. I asked him how I got it & he told me it was through sex & that I just needed to get over it.
Tonight I have come home and my daughter has used my towel to dry herself. I have irrationally spent last 30 mins crying for fear she has contracted it. I was very very ill with my first outbreak, in so much pain, lasting 4 weeks. I have told my husband I am never having sex with him ever again, or anyone else. I wanted another baby, and now all my dreams are shattered.
Posted by Laura W | May 8, 2013, 7:02 amMy tests came up positive for IgG HSV1 and negative for IgM and HSV2 – six weeks after encounter/exposure. Can the igG antibodies develop that quickly and show positive and there by making the IgM negative? or this means it could be more than likely a pre-existing condition? Pleas let me know.. Thanks.
Posted by Matt | May 8, 2013, 6:53 pmFurthermore, when I asked my provider for the IgG level, they responded me that there is no level for the HSV tests.
Posted by Matt | May 9, 2013, 2:52 pmYou mention that IgG takes several months to show up. Is there any data/literature on this? (what is the standard deviation? I imagine it could only be measured via intentional infection of animals followed by duration to seropositive result?)I came back positive for HSV-1 (HerpeSelect type-selective test), first value was a 5, second value a month later was a 7. First value was 2 weeks after a risky sexual encounter. I think this is genital HSV-1, doctor is unsure from examining me clinically, but I want to know whether to be cautious with future sexual partners. Unfortunately I was never tested before so it’s unclear if this is an antibody developed 20 years ago as a child…
Posted by Adam | May 18, 2013, 3:16 pm