Men who carry the human papillomavirus (HPV), which causes genital warts have a higher risk of human immunodeficiency virus (HIV) infection.
There are more than 100 strains of HPV, some of which cause genital and anal warts. In most people, the immune system clears the infection fairly rapidly. However, persistent infection with certain HPV strains can eventually lead to cancer in some cases. Persistent HPV infection is the primary cause of cervical cancer and it can also lead to cancers of anus and penis. To study the effect of HPV infection on HIV acquisition, researchers followed 2,168 Kenyan men between the ages of 18 and 24 years. Half of the participants tested positive for HPV at the start of the study.
Over the next 3.5 years, nearly 6 percent of HPV-positive men became infected with HIV, versus just under 4 percent of those who had tested HPV-negative at the outset. When the researchers controlled for a number of HIV risk factors, men with HPV were still 80 percent more likely than their HPV-negative counterparts to become infected with HIV, suggesting the genital wart virus itself may boost a person's susceptibility to HIV.
HPV infection itself was linked to a higher risk of acquiring HIV even when the researchers factored in circumcision, as well as the men's reported sexual history and whether they had the genital herpes virus - which has already been linked to an increased risk of HIV infection.
It's not clear why HPV infection might increase the risk of HIV infection, but it is biologically plausible that skin lesions caused by HPV, for example, might act as portals of HIV entry. In addition, HPV may induce the production of certain inflammatory proteins in the genital area, which may in turn boost susceptibility to HIV infection.
The findings raise the possibility that vaccination against the virus, known as the human papillomavirus (HPV), could help curb the world's HIV pandemic.