Australian Herpes Management Forum

Herpes transmission and safe sex

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Dr Chris Miller

People with genital herpes or cold sores can pass these conditions on to their sexual partners. It’s possible to decrease the risk of passing it on, but unfortunately it’s not as straightforward to prevent transmission as it is for other sexually transmitted infections (STIs) like chlamydia or HIV.

Safe sex tips

Some of the strategies that work well to prevent other sexually transmitted infections don’t work as well for genital herpes, because:

• Most people with herpes don’t know they have it. That means they don’t even know that they might be passing it on to their partners.
• Even people who know they have herpes or cold sores can be infectious in between outbreaks. The risk is less, but on some days, most people with herpes or cold sores release the virus from the skin—even when there’s no sign of an outbreak. The herpes virus is released from the region where herpes sores appear. This is called asymptomatic shedding. It’s the most common way of transmitting herpes or cold sores because you can’t tell when it’s happening.
• Condoms or other barriers such as dental dams can help reduce the risk of passing on the herpes virus, but they aren’t 100 per cent effective.

How herpes is transmitted

It’s helpful to have some knowledge of how herpes simplex virus—which causes both genital herpes and cold sores—is transmitted. Once you know how it works, you can understand how to reduce the risk.

The herpes simplex virus (HSV) is passed on from one person to another by skin-to-skin contact. The virus rubs off the skin of one person and into the skin of another. This happens most easily if:

• The contact is very firm and/or for a long period of time
• The skin of the person “receiving” the HSV is very soft, tender or damaged in some way.

This explains why herpes simplex is transmitted fairly easily through intercourse, oral sex or kissing. During these activities, parts of the body that shed HSV get rubbed against the parts of the body that are most easily able to receive it. It also helps explain why people don’t usually get herpes on other parts of the body.

Can you give herpes to someone who already has it?

Remember that most people carrying HSV don’t know they have it. They may never have developed any symptoms or maybe they mistook the symptoms for something else, like thrush or a skin rash.

Recent research has shown us that:

• About 12 per cent of Australians are carrying HSV-2 (the commonest cause of genital herpes)
• About 76 per cent of Australians are carrying HSV-1 (which usually causes cold sores but also causes about 40 per cent of genital herpes)

If you have genital herpes and your partner has never had an outbreak, they could still be carrying one or both strains of HSV and be unaware of it. In this situation, it’s harder for you to pass on HSV to your partner, as their immune system will recognise it and stop it from entering their body again. Even if you have HSV-2 and they only have HSV-1, they will still get some protection from their immune system. They might get the virus from you, but the chances are they won’t ever get a serious outbreak. This is reassuring news, as most people already have HSV-1.

The herpes blood test: type-specific serology

Many couples where one partner has herpes choose to have a blood test (type-specific HSV serology) to learn whether the other partner is at risk. Reasons for having this test include:

• Long-term relationships where the couple is considering relaxing their safer sex activities
• Where a woman with no history of herpes is planning to fall pregnant. (If there’s no evidence of herpes, she will need to be very careful not to get the virus from her partner during the pregnancy as it can be dangerous for the baby.)

If both partners test positive for the same strain of HSV, it’s unlikely one partner could pass it to the other and they would normally not need to take any precautions to prevent transmission.

If one partner has HSV-1 and/or HSV-2 and the other doesn’t, the couple is said to be serodiscordant. The negative partner is potentially at risk of getting HSV from the positive partner and the couple may choose to reduce the risk of transmission in various ways.

Risk Behaviour - Rating the risks

With herpes transmission, it’s better to think of the risks along a scale, rather than simply “safe” or “not safe”. The following charts can help you decide which things you’d like to do to reduce the risk of transmitting HSV. This information is more relevant to couples who are serodiscordant or haven’t had type-specific serology.

Cold sores/Oral herpes

Genital herpes

The Australian Herpes Management Forum

The Australian Herpes Management Forum is a group of medical experts that provides resources and information about the herpes group of viruses and the conditions they cause. These include genital herpes, shingles, chickenpox, glandular fever and cold sores. If you are concerned about herpes or think that you may have come into contact with someone that has herpes, please see a doctor.

  

More information about herpes

Genital Herpes Essential Facts Herpes Myths... Debunked Herpes Transmission and Safe Sex Herpes Treatments Testing for Herpes Non-sexual transmission of herpes What does it mean for partners? Herpes & Pregnancy Herpetic Dermatitis & Whitlow

 

Where can I go for help?

To find a public sexual health clinic near you, see the Register of Public Sexual Health Clinics (published by the Australasian Chapter of Sexual Health Medicine)