Transmission of sexually transmitted and blood-borne infections (STBBIs)

As the name suggests, sexually transmitted and blood-borne infections (STBBIs) are either sexually transmitted, blood borne, or both.

Having sex without a condom is the most common way to get an STBBI. But depending on the infection, they can be transmitted in other ways.

STBBIs are mainly transmitted in four ways:

• During oral, vaginal, anal sexual contact or skin to skin contact
• Through blood when sharing drug injection or inhalation equipment
• Through blood during tattooing or piercing with contaminated equipment
• From an infected mother to her child during pregnancy, childbirth or breastfeeding

An infected person can pass an STBBI on without even knowing they are infected, since most infected people do not have any symptoms. An STBBI can affect health, even when there are no symptoms.

So many people are unaware that they are infected. This is the case for:

• 9 in 10 people who have genital herpes
• 9 in 10 people who have human papillomavirus (HPV)
• 3 in 4 people who have chlamydia
• 1 in 5 people who have human immunodeficiency virus (HIV)
• 1 in 5 people who have hepatitis C

By using condoms or dental dams and taking precautions when using equipment where there is a risk of transmission, you can avoid the risk of getting an STBBI.

Stopping using condoms should only be considered after both partners have been tested, even if the they find themselves after a break in a previously stable and faithful relationship.

During sex, STBBIs are transmitted when there is contact between mucous membranes and infected semen, vaginal secretions or blood, for example during:

• Oral sex (the mouth comes into contact with another person’s penis, vulva, vagina, or anus)
• Vaginal intercourse (penetration of the penis into the vagina)
• Anal intercourse (penetration of the penis into the anus)
• Contact between the partners’ genitals (the genitals touch, but there is not necessarily penetration)
• Direct contact of the skin or mucous membranes with the chancre or rash of an infected person
• Sharing of sex toys

STBBIs’ transmission during sexual activities can occur without penetration, orgasm or ejaculation.

Using a condom is a simple way to protect yourself from STBBIs during sex. To be fully effective, it must be used before any contact between the penis and the mouth, vagina or anus, from start to finish of sexual intercourse. However, HPV, herpes and syphilis can cause lesions on areas that are not covered by the condom. This means transmission can occur in areas such as the thighs, buttocks, testicles, etc. Using condoms cannot guarantee total protection, but is the preferred method.

Removing the penis before ejaculation does not protect effectively against STBBIs. Without a condom, an STBBI can be transmitted when the penis touches the vaginal mucous membranes or invisible lesions.

Some STBBIs can be contracted during oral sex, even if the person does not have any symptoms. The risk is low, but still real.

Using a condom for oral sex provides effective protection. Flavoured condoms are designed for this and come in a variety of flavours.

Sharing equipment to prepare, inject and inhale drugs (cocaine, heroin or steroids for example) is associated with a risk of contracting several STBBIs such as hepatitis B and C and HIV.

Blood, even in tiny amounts, may be present on the shared straw, syringe or crack pipe.

To reduce the risk of STBBI transmission through injection or inhalation drug use, use your own equipment and avoid sharing it.

Handling a used syringe that does not belong to you is also dangerous. To find out how to dispose of used syringes safely, go to the page Used syringes: what to do to prevent accidents and the transmission of infections.

Sharing needles and instruments used for tattooing and piercing is associated with a risk of STBBI transmission, including hepatitis B and C and HIV. The equipment may have been in contact with blood. To be sure the equipment does not contain contaminated blood, new or sterilized equipment must be used.

Sharing personal items, such as a razor, toothbrush, nail clippers or sex toy, carries a low risk of STBBI transmission. There is a risk when contaminated secretions or blood come into contact with:

• the surface of damaged skin (bite, sting, cut or wound)
• a mucous membrane (for example, membrane lining the mouth or nose)

Sex toys should be covered with a condom and the condom must be changed after each penetration.

At your partner’s house or when travelling, each person should use their own personal items.

Everyday activities, such as going to the same school as an infected person, sharing a meal, drinking from the same glass, kissing them on the mouth, hugging them, etc., do not lead to the transmission of viruses through blood or sexual contact. There is no risk from being around someone who has a sexually transmitted or blood borne infection, but some precautions must be taken if you have sex with them or share drug injection or inhalation equipment.

A pregnant person who has an STBBI can transmit it to the fetus during pregnancy or to the newborn during delivery. During breastfeeding, only HIV can be transmitted.

To find out more, go to the page Sexually transmitted and blood-borne infections (STBBIs) and pregnancy.