Herpes simplex viruses include two distinct but closely related viruses, namely, herpes simplex 1 (HSV-1) and herpes simplex 2 HSV-2. Both viruses can cause genital herpes. Roughly speaking, HSV-2 causes 90% and HSV-1 causes 10% of all genital herpes. Herpes simplex virus is a linear double-stranded DNA virus. HSV-1 and HSV-2 share approximately 50% homology of their genetic materials and they even express type-common surface antigens. It accounts for the high degree of cross-reactivity and the technical difficulty in differentiating the 2 viruses. On the other hand, HSV-1 & HSV-2 antibodies offer some degree of cross protection. Cell-mediated immune responses is more important than humoral responses in determining the severity of HSV infections. Hence, AIDS patients often have chronic and severe anogenital herpes. Genital herpes is usually transmitted by sexual intercourse. Direct inoculation of virus occurs through contact with infected secretions or mucosal surfaces. Orogenital contact with a partner with type 1 herpes labialis can also result in genital herpes. Asymptomatic shedding of HSV is the most common mode of transmission of genital herpes infection. It is estimated that more than half of the HSV-2 genital infections are asymptomatic.
Transmission is caused by close oral, anal, or genital contact, including intercourse, masturbation, kissing, or any direct skin-to-skin contact which allows for the transfer of bodily fluids.
