How is HIV transmitted between people?

Who is at risk of getting HIV, and how?

How sexual behaviour relates to the spread of HIV:

Risks are associated mainly with sexual behaviour. HIV is transmitted through the exchange of body fluids. Almost 80% of transmission is through the sexual exchange of body fluids.

The majority of people  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. Most bodily fluids are infectious. Infectious bodily fluids include:

• Blood, all bodily fluids containing blood.
• Vaginal secretions.
• Semen.
• Saliva.*
• Pericardial fluid nasal secretions.*
• Peritoneal fluid vomit.*
• Pleural fluid faeces.*
• Cerebrospinal fluid urine.*
• Amniotic.

NB. If any of the above is mixed with blood they could be considered infectious.

How is HIV spread through ‘mother-to-child transmission’?

Mother-to-child transmission of HIV accounts 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.

How else is HIV spread or transmitted?

• Intravenous drug use: Up to 10%.
• Blood transfusions: 5%.
• Exposure to infection through needles etc.: 0.01%.
• 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 injuries  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.
• Transmission from mother to infant, with AZT treatment: Less than 1 in 10.
• Transmission from mother to infant, with combination antiretroviral therapy: 1 in 50.

Related articles