Genital Herpes Screening and Diagnosis

There are a wide variety of methods of diagnosis genital herpes. The journey to diagnosing this disease begins with a visit to a healthcare provider.

Clinical Diagnosis

A clinical diagnosis of herpes begins with a history and physical examination by a healthcare professional (nurse practitioner, physician’s assistant or a physician). During the history, you will provide as much accurate information about your symptoms as you can. Important details include sexual history, any symptoms that your partner may have, any symptoms you have and when these symptoms started. During the physical examination, your provider will inspect any lesions or areas of concern. Your provider will then combine the information you have given with what he or she finds on physical exam to determine what the most likely diagnosis.

The accuracy of the clinical diagnosis will depend on the clinician, the history you provide and what (if anything) is seen on physical exam. A clinical diagnosis can be reliable in many cases. However, the ulcers caused by genital herpes may look like ulcers from other diseases such as syphilis, chancroid, Behcet’s disease and a few other conditions. Therefore if there is any doubt regarding the diagnosis or if your symptoms are not “typical” for genital herpes, laboratory testing can be used to make a more definitive diagnosis. Laboratory testing is also suggested to confirm a clinical diagnosis.

Laboratory Diagnosis

Viral Culture

A viral culture involves taking a sample from an active lesion. An active lesion is a vesicle (blister) or an ulcer. The clinician will need to puncture the roof of the blister remove fluid from it. If an ulcer is present, a swab will be used to take a sample from the base of the ulcer. The viruses will usually grow in the culture by 5 days. This test is most accurate when the lesion is in the early blister stage rather than in the later stages when the lesion has crust on it. The ability of this test to detect the virus is also higher with the first herpes outbreak rather than during a recurrence. Once the virus has grown, the type (HSV-1 or HSV-2) can then be determined by further testing.

Polymerase Chain Reaction

Polymerase chain reaction (PCR) involves taking a sample from a lesion or a genital area (vagina, cervix, rectum or penis) and analyzing it for the DNA of the herpes virus. This test is more sensitive than viral culture and can be done rapidly such that the results are available in the same day. This utility of this test is reduced by its limited availability and lack of standardization for a variety of samples.


Cytology involves directly examining individual cells.

A Papinicolaou smear (Pap smear) is a test usually used to screen for cervical cancer. This test can also detect cells infected with HSV even if the woman does not have symptoms. This is not a usual method of diagnosis.

A Tzanck smear requires a sample from an active genital lesion. It is limited in utility because it is not very sensitive and does not distinguish between HSV-1 or HSV-2.

Direct Fluorescent Antibody

Direct Fluorescent Antibody (DFA) relies on samples from lesions. This test is sensitive and able to distinguish between HSV-1 and HSV-2 but can at time deliver falsely positive results.

Serologic Testing

Serologic tests analyze blood samples. When a foreign substance (an antigen) enters the bloodstream, the body’s immune system forms a protein called an antibody to help fight the antigen. When someone is infected with the herpes virus (an antigen) the body will form an antibody against it within 10-20 days. There are two main antibodies formed against herpes, Immunoglobulin M (IgM) and Immunoglobulin G (IgG). IgM antibodies are the first to be formed and can usually be detected in the blood 9-10 days after an exposure to the virus. They will usually last for 7-14 days but some people may have them for up to six weeks. IgG antibodies develop later than IgM antibodies. It may take several weeks to months for them to develop.

The Herpeselect tests can test for the herpes virus antibodies and distinguish between HSV-1 and HSV-2. The tests are based on the antigen glycoprotein G1 (gG1) that is specific to HSV-1 and the antigen glycoprotein G2 (gG2) that is specific to HSV-2. Herpeselect has two types of tests: the immunoblot and the ELISA. Though the laboratory methods of the two tests differ, the principle is the same: detecting IgG antibodies in your blood that interact with either the HSV-1 (gG1) or the HSV-2 (gG2) antigens. These tests are very sensitive and can detect the herpes simplex antibodies in the blood even if you are not having symptoms.

If the test is positive, that means the IgG antibodies to herpes simplex were found in your blood. The test will determine if you have antibodies to the HSV-1, HSV-2, or both. Having the HSV-1 or HSV-2 IgG antibodies in your blood means that you have been exposed to the herpes virus and have been infected. A positive test for HSV-2 antibodies in the blood likely represents genital infection. Because HSV-1 infections can occur in the genital area or the mouth, a positive test for HSV-1 antibodies cannot tell you whether the infection is in the genitals or the mouth. This test cannot tell you when you were infected. The amount of antibody in the blood does not coordinate with the severity of the infection or how well medications are working to treat the infection. If the test is negative, it means that you are either not infected OR the infection happened so recently that your body has not had time to react.

While Herpeselect tests for the IgG antibody, it does not test for IgM. There are tests available to look for IgM. If the test for herpes virus IgM is positive, the usual assumption is that the infection is recent. However, IgM levels can also be elevated in individuals who are having a recurrence of herpes. If this is the case, the level of antibody will usually be lower than in the initial infection. The tests available for IgM do not distinguish between HSV-1 and HSV-2.

Disclaimer: This article is not meant to provide specific medical advice and is not a substitute for an examination by a physician or other qualified healthcare professional.


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