Proximate and underlying determinants of HIV infection.

Socio-demographic characteristics influence HIV infection status via proximate factors (sexual risk behaviours) which in turn modify the biological risk of HIV infection. For instance, the number of sexual partners, non-regular partners, concurrent partners, transactional sex and age of sexual debut influence the probability of exposure of susceptible to infected individuals, while condom use, concomitant STIs and medical circumcision affect the efficiency of transmission per sexual contact. * Alcohol use is considered as a background factor as it is believed that its impact on HIV infection is mediated by sexual risk behaviours.