Risks and modes of transmission
Risks are associated mainly with sexual behaviour. HIV is transmitted through the exchange of body fluids and is principally sexually transmitted as this is the main means of such exchange. Almost 80% of transmission is through the sexual exchange of body fluids.
1. Anal Sex Very high: The rectum is a fragile tissue prone to tears when penetration occurs.
2. Dry Sex Very high: Involves the removal of the natural lubrication of the vaginal tract, a sexual preference amongst some males.
3. Vaginal Sex High: With increased risk when the woman is menstruating and also high risk with the presence of sexually transmitted diseases.
4. Kissing, deep throat and lip contact Low-Medium: Risk may be increased with poor oral hygiene which includes the presence of bleeding gums or sores.
5. Oral Sex Low-Medium: Risk may be increased with poor oral hygiene which includes the presence of bleeding gums or sores.
6. Sex with a condom, femidom Very low: Providing the condom is good quality and is placed over the penis correctly or the femidom is inserted correctly.
7. Intimate Touching Nil-Low: Risk increases if finger penetration occurs and cuts occur at the base of the fingernails.
8. Abstinence Nil: No sexual practices equals no risk.
The majority of people that are infected with HIV are likely to have acquired the infection sexually. HIV is present in the majority of bodily fluids – some of which are infectious and some of which are not. The majority of bodily fluids are infectious.
- Infectious bodily fluids.
- Blood, all bodily fluids containing blood.
- Vaginal secretions.
- Semen saliva.*
- Pericardial fluid nasal secretions.*
- Peritoneal fluid vomit.*
- Pleural fluid faeces.*
- Cerebrospinal fluid urine.*
NB. If any of the above is mixed with blood they could be considered infectious.
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 US, 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 include:
- Intravenous drug use: Up to 10%.
- Blood transfusions: 5%.
- Exposure to infection through needles etc.: 0.01%.
- Infection Route Sexual Intercourse Risk of Infection.
- Female-to-male transmission 1 in 700 to 1 in 3000.
- Male-to-female transmission 1 in 200 to 1 in 2000.
- Male-to-male transmission 1 in 10 to 1 in 1600.
- 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.