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Gathered from Viridae Clinical Sciences Inc.
Introduction
Genital Herpes is caused by a common virus known as Herpes Simplex. Because of certain differences in laboratory characteristics, scientists have designated herpes strains as either type 1 or type 2. Type 1 generally causes cold sores around the mouth, while type 2 generally causes sores on the genital area. In other words, most often, genital herpes is caused by herpes simplex virus type 2. However, the word "genital" actually refers only to the area of skin affected not to the virus type. In fact, a person may get genital herpes from the mouth of a sexual partner with an active herpes simplex virus type 1 infection (e.g., a cold sore) during oral sex. In this case, this person will get type 1 genital herpes. Genital herpes is a sexually transmitted disease (STD) and is usually passed on through genital skin contact with an area affected by an active herpes sore in the partner. After herpes is contracted, it usually causes a skin infection which clears by itself (or faster with treatment). After the illness is over, the virus in the skin has been removed from the area by the body's immune system. Between outbreaks, the virus hides in certain nerve cells (neurons) along the lower spinal cord in a place called the sacral ganglia. The virus will remain there in an inactive or latent phase, although it may reoccur from time to time and travel back down the nerve to the skin.
If you think you have genital herpes, go to a clinic or a Doctor to have it diagnosed. Diagnosis is made based on clinical symptoms and/or a viral culture. If you feel you are having your first or primary episode, this should be diagnosed through a blood test in combination with a viral culture. In some situations, genital herpes may be a simple diagnosis for the general practitioner. In others it may even elude the specialist. When symptoms and signs of herpes are "classical", that is, when a known exposure has taken place and sores have developed that are painful clustered vesicles (blisters) or ulcers on a red, inflamed base, the clinical diagnosis is clear-cut. Recurrences make herpes even more likely. Then, the virus itself is detected by a culture test from one of the sores, confirming the diagnosis. In order to make sure that no other diseases accompany the herpes, tests for syphilis, gonorrhea, Chlamydia, trichomonas and yeast are also performed.
Certain people with genital herpes can have mild intermittent symptoms. The only sore might be a pinpoint or single ulcer on the labia that lasts for a few days and reoccurs every six months. It may not hurt at all. The diagnosis may not even occur to the patient or the physician. A virus culture test to detect herpes in the sore should be performed during an active phase of infection. If the test is positive, herpes is likely to be the cause of the sore. A positive culture for herpes simplex virus from the skin means that you have herpes. The virus culture is so reliable, it is called the gold standard for this infection.
If the culture test is negative, however, herpes may or may not by the cause of the problem. The following issues need to be considered if a test comes back negative:
 | was the test obtained during an active period? Even if it was, quite often herpes virus is not recoverable. Correct timing of the virus culture is essential. |
| how was the test obtained? |
| was the doctor's office far away from the laboratory? If so, the virus may not have survived the trip. |
| how experienced is the laboratory? This varies. |
If you suspect herpes and your doctor agrees, return again for virus culture at the first sign of a recurrence. The earlier the specimen is obtained, the better is the chance of an accurate test. In my experience, two visits will suffice, if the visits are early. If we suspect herpes very strongly, however, we will keep culturing until we find it. Rarely, four or five tests are necessary.
Blood Test (Top of page)
Blood tests have markedly improved the physicians' ability to properly counsel both patients and their partners. Herpes blood tests measure the body's immune response against the virus. Without infection there is no specific reaction to the virus. However, shortly after true viral infection the body responds to fight the infection. The herpes blood test measures the body's antibodies to herpes, the body's response to infection. A positive blood test indicates there are antibodies present, therefore viral infection has occurred; a negative test indicates antibodies are nonexistent. All herpes antibody tests do essentially the same thing. They do not directly measure virus but the body's reaction to the virus. To look directly for virus, one must test a sore containing virus and grow the virus in the laboratory. This has the advantage of determining the virus and its type.
Blood tests will not identify a sore or its position, but an accurate blood test could be used to help diagnose herpes in people who do not get sores and in people who get them only rarely. People who might want such a test would include:
| the partner who has no symptoms but who may have been the source of herpes |
| the person with only one past episode whose culture was lost on the way to the lab |
| the person who thinks he or she has been exposed to herpes but is not sure |
| the couple who wants to give up safer sex precautions. |
Unfortunately, the commercial tests available to your health care provider can be very confusing. Most herpes antibody (blood) tests are not truly type specific. Most antibody tests cannot accurately tell the difference between past infection with type 1 versus type 2. To further confuse things, even some widely used tests that are commonly called "type specific" are not accurately type-specific. Most commercial type specific tests are very poor at accurately differentiating antibody against herpes simplex virus type 1 from antibody against herpes simplex type 2. Many of these inaccurate tests are commercially available and they may be easily accessible to your doctor.
Inaccurate type specific or non typespecific blood tests are still useful in some settings. For example, during a first episode, an antibody test may be used, in conjunction with viral culture and typing, to determine whether that culture proven episode is a true primary or a non primary. In this case, the blood test is not used to diagnose genital herpes but whether it's a true primary; the culture and typing of a lesion specimen was used to make the diagnosis of genital herpes.
Recently, true and accurate type specific antibody tests for herpes have been developed. These tests examine directly for the body's reaction (antibody production) against a type2specific glycoprotein, Gd (gG2). Very few laboratories test directly for this antibody, since commercial test kits are not routinely available for this purpose. Until new tests replace the old tests, you and your physician will have to interpret information obtained very carefully.
The Western Blot test is so specific that, as far as we can tell, there is virtually no chance for error of the type that shows a positive antibody to herpes simplex virus type 2 where none exists. On the other hand, there is always a small possibility that an antibodies to herpes simplex virus type 2 that is really present will go undetected by this method. This could happen in the case of a person who has not had time to make a good antibody response yet. In some cases, antibody may take as much as twelve or sixteen weeks to develop, especially if the primary infection was treated with an effective medication. In some rare cases, a person with culture proven, long-lasting, herpes type 2 of the recurrent variety will still have a negative Western blot after the sixteen weeks presumably because they just do not make enough of the necessary antibody for detection. This probably occurs less than 1 percent of the time.
The Western Blot is very, very sensitive probably 99 percent sensitive. It is also very accurate, with virtually no false positives (incorrect positive results). If a person is tested more than twelve or sixteen weeks after the possible exposure, and if the test is negative, and if the possible exposure was to type 2 herpes simplex virus, then it is very likely that bona fide infection did not take place. However, no test is absolutely without fault and this test, like all tests, should be interpreted by you and your physician, in the seeing of the clinical information, so that everyone understands all of the subtle details.
Other tests for gG2 (type2specific glycoprotein), called RIA, ELISA, or EIA (other names are also possible) may also be available. These tests can determine whether there has been infection we herpes simplex virus type 2, but they do not necessarily determine whether there has been infection with type 1. EIA tests are technically much easier to perform than the Western blot, with much of the assay actually done by machine. Unfortunately, commercial kit assays for antibody to gG2 are not yet available. This situation is very likely to change and soon. ELISA tests have been successfully used for this purpose, with one described from Atlanta, one from California, another from Sweden, and an adaptation from Australia.
Until then, if possible, be especially careful to check with your physician as to which test is being ordered and how the test will be interpreted before actually being tested. The test situation can be very confusing, because if your physician has ordered a so-called type specific EIA test that does not specifically check for antibody against gG2 or some other type 2 specific glycoprotein, then the test answer may be of no value and should not be interpreted. So called type specific tests that often give misleading test results are most often reported as "type 2:type 1 ratios." Always check this out with your physician.
When to do a Western blot (Top of page)
The following are some examples of real cases where we have found the Western blot test to be especially useful. Test results will be different for each person depending upon their own experience.
Example 1: A couple in a long-term relationship wish to be tested for herpes. One partner has genital herpes simplex virus type 2 proven by viral culture. The other partner is asymptomatic, although they have been together for several years. The partner wants to know if he or she is still at risk of getting genital herpes.
Serology Results: There is virtually never a need to perform a Western blot in a person with viral culture proven type 2 genital herpes simplex virus infection, since the viral culture (if it is positive) tells you the information you need. However, the partner should be tested. In this case, he or she is seropositive for HSV type 2.
Interpretation: This partner has genital herpes. He or she may have had genital herpes at the time the couple met, or asymptomatic transmission may have taken place at some point in their relationship. Either way, there is very little risk for the partner catching a second infection with type 2 herpes simplex virus. This couple can relax significantly their concerns about transmission of genital herpes since both already have proven infections. While there are cases of second viral strain transmission, the chance of that being a problem for this couple is very remote.
Example 2: A patient with a history of genital herpes is seen twelve months after recovering from genital sores diagnosed by only visual examination as probable primary genital herpes. A virus culture performed at the time was negative, but the patient's physician explained that the negative result does not rule out genital herpes. The patient was advised to return with an active episode for repeat culture, but none have been detected. The patient has had one monogamous relationship, which started just before the so-called primary infection, with a partner who has no history of genital symptoms. They commonly practice oral genital sex. Neither partner has cold sores.
Serology result: Both partners are positive for HSV type 1 and negative for HSV type 2.
Interpretation: Blood tests results must be interpreted in the clinical setting. It is very likely that the patient's partner does not have genital herpes. The patient's genital sores may have been a primary genital episode, but, if so, probably resulted from oral genital transmission of HSV type 1 from the partner. Regardless, the prognosis for a continuing low genital recurrence rate is excellent. Alternatively, these blood test results are consistent with both patient and partner having been exposed on the face to cold sores at some time in their lives, while neither has genital herpes at all. A third explanation would be that the partner transmitted herpes simplex virus type 1 to the patient by genital contact with asymptomatic genital herpes simplex virus type 1 sores. Alternative diagnoses to the patient's primary herpes diagnosis should be considered, especially if symptoms recur frequently. The serology test is only additional supportive evidence for the diagnosis. It does not determine where in the body exposure has taken place, and it must be interpreted cautiously and in connection with the clinical picture. This patient with genital sores should be quite certain that other causes of genital ulcer have been ruled out, since the precise is not yet know. In this case, the serology test has helped to rule out some things but has not specifically confirmed the clinical problem. It is very important that this patient be tested for syphilis to make sure that syphilis did not cause the ulcer, since syphilitic ulcers, left untreated, will improve and then remain dormant only to cause damage later on. The result above could be consistent with both patient and partner having immunity to herpes simplex virus type 1 from asymptomatic mouth cold sores and with one partner having transmitted syphilis to the other that has never been diagnosed or treated. Without a test, nobody will know.
Alternative Serology Result: Both partners are negative for both HSV type 1 and HSV type 2.
Interpretation: The initial diagnosis of genital herpes was probably incorrect. An alternative diagnosis should be considered, but if the infection remains inactive, the cause may never come to light. The syphilis test discussed above is crucial, although the result is likely to be negative. If sores are recurrent, one or more specialist physicians should be involved to try to sort out the proper diagnosis.
Summary (Top of page)
Type specific serology testing is especially useful in unusual presentations of herpes and in some asymptomatic cases. People with genital sores will still need to have a viral culture test from a sore for confirmation and typing. The culture test is more direct, less expensive and provides information about the specific sore and the symptoms. If you have a clear positive viral culture test that is typed (type 1 vs. type 2) there is almost never a reason to get a Western blot also.
A negative Western blot test performed correctly, means that genital herpes is very unlikely, although there is still a small chance of a false negative. A positive test for type 2 herpes strongly suggests the diagnosis of genital herpes, although the test does not determine the site of infection. Although most type 2 herpes is sexually transmitted and usually affects areas on or near the genitals of anus, there are type 2 facial herpes infections as well. Furthermore, since genital herpes can be caused by type 1 herpes simplex virus, a negative test for type 2 does not rule out genital herpes: it only makes type 2 genital herpes very unlikely, as long as the twelve to sixteen weeks' waiting period has passed. It may take up to twelve to sixteen weeks after infection for the serology test to show positive. Any test result should be interpreted with your physician.
If you feel you require a Western blot, see Requesting Western Blot Serology for HSV and Specimen Submission Information and discuss it with your family doctor.