ABSTRACT
A prior herpes simplex virus (HSV)-1 infection will generally prevent a genital HSV-1 infection, but only infrequently will it prevent a genital HSV-2 infection. Individuals with such initial first HSV-2 infections usually demonstrate lesser clinical manifestations than primary ones. The different transmission patterns assumed by HSV-1 via saliva, sexual transmission, or from mother to progeny are well exemplified in several lower species naturally infected with their own α herpesviruses. Clinical isolates could also be differentiated into distinct variants within each type, using restriction enzyme analyses, opening the way to studies on the "molecular epidemiology" of HSV. The decline in the prevalence of HSV-1 antibodies in the younger age groups among higher socioeconomic status populations in various countries represents one of the major factors responsible for the increasing trends of genital HSV-1 infections. The more general availability of viral typing and antibody-type differentiation has provided a wider perspective of HSV-1 and HSV-2 infections in several areas of the world.
