A prospective study of new infections with herpes simplex virus type 1 andtype 2

Background Herpes simplex virus (HSV) infections are endemic, but the clini cal characteristics of newly acquired HSV type 1 (HSV-1) and HSV type 2 (HS V-2) infections in adults have not been rigorously defined. Methods We monitored 2393 sexually active HSV-2-seronegative persons for cl inical and serologic evidence of new HSV infection. Of the participants, 15 08 were seropositive for HSV-1 and 885 were seronegative. Charts were revie wed in a blinded manner for classification of those with genitourinary or o ropharyngeal symptoms. Charts were also reviewed for all 174 persons with H SV seroconversion. Results The rates of new HSV-1 and HSV-2 infections were 1.6 and 5.1 cases per 100 person-years, respectively. Of the 155 new HSV-2 infections, 57 (37 percent) were symptomatic, 47 of which (82 percent) were correctly diagnos ed at presentation. Among the 74 patients given a clinical diagnosis of gen ital HSV-2 infection during the study, 60 were given a correct diagnosis an d 14 were given an incorrect diagnosis, for a ratio of true positive result s to false positive results of 4:1. Among the 98 persons with asymptomatic HSV-2 seroconversion, 15 percent had genital lesions at some time during fo llow-up. Women were more likely than men to acquire HSV-2 (P<0.01) and to h ave symptomatic infection. Previous HSV-1 infection did not reduce the rate of HSV-2 infection, but it did increase the likelihood of asymptomatic ser oconversion, as compared with symptomatic seroconversion, by a factor of 2. 6 (P<0.001). Of the 19 new HSV-1 infections, 12 were symptomatic. The rates of symptomatic genital HSV-1 infection and oropharyngeal HSV-1 infection w ere the same (0.5 case per 100 person-years). Conclusions Nearly 40 percent of newly acquired HSV-2 infections and nearly two thirds of new HSV-1 infections are symptomatic. Among sexually active adults, new genital HSV-1 infections are as common as new oropharyngeal HSV -1 infections. (N Engl J Med 1999;341:1432-8.) (C)1999, Massachusetts Medic al Society.