Male Circumcision and HIV Transmission; What Do We Know?

Male circumcision (MC) has been shown to be protective against heterosexual HIV transmission and is being explored in some parts of the world as a means of combating the epidemic. The World Health Organization (WHO) recommends that MC be considered as an important component of HIV prevention in high prevalence settings. We review evidence that demonstrates that the inner foreskin is likely to be the main portal of entry for the HIV virus in males. Whether removal of the inner foreskin accounts for all the protection afforded by circumcision is yet to be established. The proposed mechanisms of protection range from inherent immunohistological factors of foreskin such as difference in thickness of keratin layer and density of target cells for HIV between inner and outer foreskin to physiological mechanisms that follow male circumcision such as drying of secretions underneath foreskin after sexual intercourse, loss of microbiome that attract target cells to the genital mucosa and lack of priming the genital mucosa with less abundant sexual transmitted infections among circumcised men. The aim of this review is to give an updated account on the mechanisms proposed so far on the demonstrated 50-70% protection from HIV transmission through heterosexual intercourse, by male circumcision.