How HIV is transmitted


We all have some knowledge of how HIV is transmitted, but what are the facts? Dr Avron Urison breaks down the detailed facts.

Sexual Transmission

HIV is transmitted through the exchange of body fluids, and thus is principally sexually transmitted, since this is the main means of such exchange. Almost 80% of transmission is through sexual exchange of body fluids.




Anal sex

Very high

The rectum is a fragile tissue prone to tears when penetration occurs.

Dry sex

Very high

It involves the removal of the natural lubrication in the vaginal tract, increasing risk of tearing.

Vaginal sex


Risk increases during a woman’s menstrual cycle, and also with the presence of sexually transmitted diseases.

Kissing, lip contact


Risk may be increased through poor oral hygiene, which includes the presence of bleeding gums and sores.

Oral sex


Risk may be increased through poor oral hygiene, which includes the presence of bleeding gums and sores.

Sex with a condom / femidom

Very low

Providing the condom is of good quality and is placed over the penis correctly, or the femidom inserted into the vagina correctly.

Intimate Touching


Risk increases if finger penetration occurs, with cuts at the base of the finger nails.



No sexual practices equals no risk

The risk of sexual transmission of HIV varies vastly, due to a variety of factors:

  • The stage of the disease of the infected person (individuals at the time of infection and at the advanced stages of the disease have higher levels of virus in their blood and are therefore likely to be more infectious)
  • The type of strain of HIV
  • The infecting persons sexual health (for example: the presence or absence of sexually transmitted diseases)
  • The sexual health of the person who may become infected (presence or absence of sexually transmitted diseases)
  • Age (Youngsters are at greater risk due to lifestyle and greater libido, desire for sex)
  • New research shows that uncircumcised men are at greater risk

Mother to child transmission

The second principle means of transmission is by means of mother to child transmission, accounting for some 630,000 infections annually in Africa. In the USA, where treatment is readily available for individuals and mothers affected by HIV, the number of infections by this means, in 2003–2004, was less than 200.

Other routes of transmission

        These include:

  • Intravenous drug use: Up to 10%
  • Blood transfusions: 5% and
  • Exposure to infection through needles etc.: 0.01%

Infection Risk

Infection route

Sexual Intercourse

Risk of Infection


Female-to-male transmission

1 in 250

Male-to-female transmission

1 in 120

Male-to-male transmission

1 in 10

Oral Sex

6%-8% of transmission



Needle stick

1 in 200

Needle sharing

1 in 150

Transfusion of infected blood

95 in 100

Transmission from mother to infant


Without AZT treatment

1 in 3–5

With AZT treatment

Less than 1 in 10

Combination antiretroviral therapy

1 in 50

 Infectious and non-infectious body fluids

HIV is present in the majority of body fluids, some of which are infectious and some of which are not. The majority of body fluids are infectious but many people believe that any body fluid is infectious.

Infectious Body Fluids

Non Infectious Body Fluids

Blood, all body fluids containing blood


Vaginal secretions




Pericardial fluid (surrounding the heart)

Nasal secretions*

Peritoneal fluid (covering organs in abdomen)


Pleural fluid (surrounding lungs)


Cerebrospinal fluid (inside spinal cord and brain)


Amniotic fluid (surrounds child in womb)


*If any of the above are mixed with blood they could be considered infectious

(Dr Avron Urison, February 2012)

 Dr Avron Urison is Medical Director at AllLife Pty Ltd - providers of life insurance for HIV positive individuals –

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