5 ways how HIV is transmitted 

The 1^st of December is World Aids Day and while HIV/AIDS is still the very real threat, great strides have been made in understanding the virus, its transmission and treatment. Our expert takes a look at the five most common ways HIV is transmitted.

1. HIV can only be transmitted by very intimate bodily contact

This is because HIV is a very fragile organism – despite the fact that once the virus has entered the body, it can cause such devastating effects.

• Unprotected sexual intercourse is the most common means of transmission worldwide (more than 90% of cases). In South Africa, most of this is heterosexual transmission, but in some areas (such as Western Europe and North America) homosexual spread between men is the most common. As we shall see later, genital secretions are particularly prone to picking up and transmitting HIV.
• Sharing of equipment used by injecting drug users is common in certain communities. Small amounts of blood in needles and syringes left after an infected person has used the equipment contains HIV that is then injected into the bloodstream of the next user. It is important to note that injecting drug use is NOT the key risk activity for the transmission of HIV – it is the sharing of equipment.

2. Medical transmission

Inadequate sterilisation of medical materials can similarly result in the spread of infection between patients. The use of disposable, single equipment such as needles makes this very uncommon.

3. Needlestick injuries

Accidental injection with potentially infected needles (“needlestick injuries”) can result in HIV transmission. Special procedures and equipment can be used to minimise the occurrence.

4. Vertical transmission

Mother to child (“vertical”) transmission is another way of transmitting the virus. HIV can be transmitted from mother to the child at any time from conception onwards. However, it seems that most transmissions occur around the time of delivery and through breastfeeding.

“HIV is a very fragile organism – despite the fact that once the virus has entered the body, it can cause such devastating effects.”

5. Blood products

Blood products – such as blood transfusion materials – can potentially spread HIV. The risk of this is particularly likely when used in concentrated forms such as the use of Factor VIII in the treatment of haemophilia.

Unlikely methods of transmission

The above methods account for over 99% of all known HIV transmissions. Clearly, the potential exists for HIV to be transmitted by other situations where bodily fluids are exposed. However, HIV transmission is known to be very unlikely to occur in, for example:

• Bites from insects
• Kissing
• Oral sex (unless there is an obvious break in the lining of the mouth or genitals)
• Body rubbing, etc.

It is always important to keep a sense of proportion. To help us do this, you can use some figures to roughly estimate the risks of transmission for each contact. It must be stressed that these are only estimates, and that they are drawn from studies of large numbers of people. Each human being is unique – and the ability to transmit or become infected varies enormously from one individual to another.