What other body fluid, besides blood, semen, and breast milk, is known to transmit HIV?

HIV primarily spreads through certain body fluids that contain a sufficient concentration of the virus to establish an infection. Among these fluids, vaginal secretions are well-documented as a route of transmission. This is because these secretions can carry the virus, especially during activities like sexual intercourse, where there may be exposure to the mucosal surfaces of the genital tract.

While saliva can carry the virus, the concentrations in saliva are typically too low to transmit HIV. Likewise, urine does not contain the virus in significant quantities to pose a risk of transmission. Thus, while saliva and urine have been considered, they are not effective modes of HIV transmission. Therefore, the recognition of vaginal secretions as a significant fluid in the transmission of HIV emphasizes the importance of practicing safe sex to reduce the risk of infection.