title: Increasing proportion of herpes simplex virus type 1 as a cause of genital herpes infection in college students.
abstract: A retrospective review of genital herpes simplex virus (HSV) isolates collected in a university student health service over a 9-year period showed that an increasing proportion of isolates were HSV-1 rather than HSV-2. HSV-1 accounted for 78% of all genital isolates in this population by 2001, compared with 31% of isolates in 1993.
  
  
  BACKGROUND
  Herpes simplex virus (HSV) type 1 is usually thought to cause less than 30% of genital herpes infections in the United States, but the proportion of infections resulting from HSV-1 is increasing in some populations.
  
  
  OBJECTIVE
  The goal was to review the relative proportion of HSV-1 and HSV-2 as the cause of newly diagnosed genital herpes infections in a population of U.S. college students and to assess trends in the change of this proportion over time.
  
  
  METHODS
  Genital HSV isolates collected at a university student health service from 1993 to 2001 (n = 499) were reviewed retrospectively. Analyses included comparisons of isolates by HSV type, age group, and sex.
  
  
  RESULTS
  The proportion of newly diagnosed genital herpes infections resulting from HSV-1 increased from 31% in 1993 to 78% in 2001 (P <0.001, linear trend P <0.001). HSV-1 was more common in females than males, but increases were noted for both sexes. HSV-1 was more common in persons aged 16 to 21 than in persons aged 22 or older.
  
  
  CONCLUSIONS
  HSV-1 has become the most common cause of newly diagnosed genital herpes infections in this population of college students and reflects a reversal of the usual HSV-1/HSV-2 ratio.
authors.affiliation: University Health Services, University of Wisconsin-Madison, Madison, Wisconsin 53726, USA. cmrober1@wisc.edu
authors.forename: Craig M
authors.initials: CM
authors.lastname: Roberts
authors.forename: John R
authors.initials: JR
authors.lastname: Pfister
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Spear
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006558:Herpes Genitalis / Q000453:epidemiology* / Q000821:virology*; D018259:Herpesvirus 1, Human / Q000302:isolation & purification*; D018258:Herpesvirus 2, Human / Q000302:isolation & purification*; D006801:Humans; D008297:Male; D015146:Midwestern United States / Q000453:epidemiology; D013334:Students / Q000706:statistics & numerical data; D014495:Universities