Human Herpesviruses: Herpes Simplex Virus Types 1 and 2

Herpes simplex virus types 1 and 2 (HSV-1 and HSV-2) cause a variety of illnesses depending on the site of inoculation (e.g., skin, eye, genital, or oral mucosa), immune status of the host (e.g., immune competent, immune immature, or immunocompromised), and whether the infection is primary or recurrent. HSV infections are ubiquitous, occur throughout the year, and are transmitted person to person through skin-to-skin contact. Most HSV infections are asymptomatic. Primary HSV infections, including those that are asymptomatic, result in the establishment of a lifelong latent infection which causes subsequent recurrent infections. Recurrent infections, particularly asymptomatic recurrences, are principally responsible for the transmission of the viruses to susceptible individuals. Orolabial and genital HSV infections are the most prevalent HSV infections, and orolabial infections are predominantly caused by HSV-1, while genital herpes maybe caused by either virus. Both HSV-1 and HSV-2 prevalence are greater in resource-limited settings. HSV-1 infection is more prevalent with risk of acquisition beginning in infancy and early childhood while HSV-2 is principally a sexually transmitted pathogen, with increasing prevalence of infection seen in sexually experienced people beginning in adolescence. risk of infection is seen in sexually experienced people beginning in adolescence. While HSV infections are significant public health problems in and of themselves, genital HSV-2 infection is particularly problematic as it is associated with a two- to threefold increased risk for HIV infection.