Moreover, in Can anal sex cause hiv commentary on the article, Andrew Grulich and Iryna Zablotska of the University of New South Wales note the lack of data on viral load and transmission during anal sex all the studies relate to heterosexual populations. Weller S, Davis K. Lowering the viral load in the blood and rectal fluid through successful antiretroviral treatment can substantially decrease the risk of HIV transmission. This creates a risk of transmission to the insertive partner through the tissue in the urethra and on the head of the penis — particularly underneath the foreskin. Anal sex, rectal fluid, and HIV transmission. Any updates not saved will be lost.