Explanation

Herpes simplex virus type 2 antibodies (HSV-2 IgG): what is measured?

The test looks for IgG antibodies aimed specifically at herpes simplex virus type 2 (HSV-2), using a protein that only type 2 has (glycoprotein G2). IgG antibodies develop weeks to months after the first infection and then usually remain present, because the virus stays in the body for life. HSV-2 antibodies almost always point to an infection in the genital or anal area. The test does not say when you were infected, nor whether you are shedding virus at this moment.

What can it detect?

A previous infection with HSV-2 (genital herpes), even if it never caused symptoms
Whether a first herpes outbreak is a new infection or a flare-up of an older infection (together with a PCR test on a blister)

Result

What does the result mean?

Positive result

A positive result means that you have probably been infected with HSV-2 at some point, usually through sex. Most people with HSV-2 have no symptoms or symptoms they do not recognize; the virus can still be shed from time to time and passed on, even without blisters. The result cannot show when or by whom you were infected. Because HSV-2 is not very common in the Netherlands, according to the LCI guideline (RIVM) some of the positive results are false. The virus stays in the body; symptoms during an outbreak can be treated, though.

Negative result

A negative result means that no HSV-2 antibodies have been found. After a first infection it can take more than 12 weeks before type-specific antibodies can be detected. Even outside that period, according to the LCI guideline (RIVM), the test misses 10 to 20 out of 100 infections, and sometimes the antibodies disappear again. Genital herpes can also be caused by HSV-1, for example through oral sex with someone who has a cold sore; this test does not measure that.

After an abnormal result

With a positive result without symptoms, no treatment or monitoring is needed; the GP can explain the risk of transmission, condom use and informing a steady partner. Pregnant women with a suspected first genital herpes infection are referred to a gynecologist. Herpes is not notifiable.

Reliability

How reliable is the test?

According to the LCI guideline (RIVM), the type-specific HSV-2 test has a sensitivity of 80 to 90 percent and a specificity of 93 to 97 percent. With a low chance of infection, a considerable share of the positive results is therefore false. The test is mainly meaningful in a few specific situations; in people without symptoms or a specific question, the chance of a falsely positive result weighs heavily. With blisters or sores, a PCR test on the fluid from the sore is the first choice.

What can affect the result?

In a first infection, type-specific antibodies can sometimes only be detected after more than 12 weeks, so the test can still be negative even during the first flare-ups.
Sometimes the antibodies later become negative again (seroreversion), mainly described in pregnant women.
With a low chance of HSV-2, the predictive value of a positive result is limited.
The test gives no information about the moment of infection or about genital herpes caused by HSV-1.

Who it is for

Who is the test useful for?

Useful for

The result says the most if your partner has genital herpes and you do not know whether you have it too, with a suspected first genital herpes infection during pregnancy, or with repeatedly recurring genital spots without a known cause at a time when they are not visible. In people without symptoms or without such a specific question, the result changes little and falsely positive results are relatively common. With visible blisters or sores, a PCR test via the GP or the GGD (municipal public health service) is better.

How common is it?

In a national population study (Pienter-2, 2006 to 2007), about 6 in 100 inhabitants had antibodies against HSV-2. In 2023, GPs made the diagnosis of genital herpes an estimated 28,600 times, more often in women than in men. Because most infections cause no symptoms and people are not routinely tested for herpes, the true number of infections is not well known.

LCI guideline (RIVM) on herpes simplex virus infections (Woestenberg 2016); VZinfo (RIVM), 2023

Drawbacks and risks

A falsely positive result can cause unnecessary worry and tension in a relationship, especially because it cannot be established when the infection took place.
A negative result can give false reassurance, because the test misses some infections and antibodies only develop late.

Get tested