HIV Transmission

Person-to person transmission of HIV requires four conditions to be met.

Presence: HIV must be present in the person’s body fluid. HIV may be infectious in five body fluids: blood, semen, secretions in the vagina, secretions in the rectum, and breast milk. (HIV is not infectious in saliva, urine, faeces or tears.)

Quantity: HIV must be transmitted in sufficient quantity to cause infection. Medication used to treat HIV can reduce the level of HIV to extremely low, ‘undetectable’ levels. Current data suggests that persons with undetectable levels of HIV do not pose a risk for HIV transmission during sex.

Route: The body fluid containing HIV has to get into the body of the other person through an effective route. Unbroken skin forms an effective barrier, but an open wound could provide a point of entry. Mucous membranes are important points of entry – these are the moist membranes lining body cavities that are not protected by dry skin, including the rectum, vagina, urethra, and the underside of the foreskin.

Susceptibility: Finally, immune system cells which are vulnerable to infection must be present at the site of entry. Mucous membranes typically contain many of these cells (Pebody 2021).

HIV can also pass mother-to-child during pregnancy, childbirth, or breastfeeding. Antiretroviral (ARV) drugs are given to women with HIV during pregnancy and to their infants after birth to reduce the risk of mother-to-child transmission (MTCT) of HIV. ARV drugs also protect the health of women with HIV during pregnancy and after delivery (Irshad 2021).

Reference

Irshad U., Mahdy H., Tonismae T. HIV In Pregnancy. [Updated 2021 Feb 25]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK558972/

Hughes JP, Baeten JM, Lingappa JR, et al. Determinants of per-coital-act HIV-1 infectivity among African HIV-1-serodiscordant couples. J Inf Dis 2012;205(3):358-65.

Masson, L., Passmore, J. S., Liebenberg, L. J., Werner, L., Baxter, C., Arnold, K. B., . . . Abdool Karim, S. S. (2015). Genital inflammation and the risk of hiv acquisition in women. Clinical Infectious Diseases, 61(2), 260-269. doi:10.1093/cid/civ298

Nhlap N. (2019) HIV Viral Load. South African HIV Clinicians Society.
https://sahivsoc.org/Files/2019%20VL%20Training%20Updated%202.pdf

Pebody R. (2020). Estimated HIV risk per exposure. Aidsmap.com. [Reviewed 5/2020]. Retrieved 4/24/2021 from  https://www.aidsmap.com/about-hiv/estimated-hiv-risk-exposure

Pebody R. (2021). HIV transmission. Aidsmap.com. [Reviewed 2/2021]. Retrieved 4/14/2021
https://www.aidsmap.com/about-hiv/hiv-transmission