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Herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2) belong to a family of DNA viruses that include cytomegalovirus (CMV), varicella-zoster virus (VZV), Epstein-Barr virus (EBV), and human herpesviruses 6, 7, and 8 (Table 309-1). Following primary infection, herpes simplex viruses establish a latent state, in general, HSV-1 in the trigeminal ganglion and HSV-2 in the sacral ganglion. From time to time, the viruses may be reactivated, resulting in recurrent infections that may or may not be associated with symptoms. HSV-1 is usually transmitted in oral secretions, whereas HSV-2 is most often transmitted through sexual activity. HSV-1 infections occur most frequently during childhood and usually affect body sites above the waist (mouth, lips, eyes, face). HSV-2 infections occur most often during adolescence and adulthood, and involve body sites below the waist (genitalia, buttocks, thighs). Historically, the majority of infections in newborns is transmitted from the maternal genital tract and is usually caused by HSV-2.1 However, because the prevalence of genital infection with HSV-1 in the United States is increasing, a greater proportion of neonatal infections may be due to HSV-1.2,3

Table 309-1. Infections Caused by Human Herpes Viruses


Humans are the only natural reservoirs of herpes simplex virus (HSV). Infections caused by HSV have no seasonal predilection; however, geographic location, socioeconomic status, age, and race influence the prevalence of infection. Children of lower socioeconomic classes and those from developing countries contract HSV-1 earlier in life than children of more affluent socioeconomic classes and children from developed countries. Increased direct person-to-person contact occurring in crowded living conditions probably accounts for these differences.

Primary infection with herpes simplex virus type 1 (HSV-1) usually occurs in infancy or childhood, whereas primary infection with herpes simplex virus type 2 (HSV-2) occurs after the onset of ...

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