Time Trends in First Episode Genital Herpes Simplex Virus Infections in an Urban STD Clinic.

BACKGROUND: Genital herpes simplex virus type-1 (HSV-1) has emerged as the leading cause of first episode genital herpes among specific populations in the U.S., such as adolescents, young adult women, and men who have sex with men (MSM). We examined trends in the etiology of first episode genital herpes diagnoses over time in an STD clinic population.

METHODS: Using an electronic database, we identified persons diagnosed with first episode genital herpes at Public Health Seattle & King County STD Clinic from 1993 through 2014 and compared risk factors for genital HSV-1 versus HSV-2 infection.

RESULTS: Of 52,030 patients with genital ulcers, 3,065 (6.15%) had first episode genital herpes infection: 1,022 (33.3%) with HSV-1 and 2,043 (67.7%) with HSV-2. Overall, 1,154 (37.7%) were women, the median age was 28 (IQR 24 to 36) years, 1,875 (61.2%) patients were white, and 353 (11.5%) were MSM. The number of patients diagnosed with first episode genital HSV-2 declined on average by 5.5 persons per year - from 208 in 1993 to 35 in 2014 (change of -5.6 per year, 95% CI=-6.9 to -4.1), while HSV-1 diagnoses remained stable at approximately 50 per year (change of 0.2; 95% CI: -0.4 to 0.9). In a multivariate model, persons diagnosed with first episode genital HSV-1 rather than genital HSV-2 infection were more likely to be younger (age <30 years (RR=1.38; 95% CI: 1.22, 1.55)), white (RR=3.16; 95% CI: 2.57, 3.88), and MSM (RR=1.50; 95% CI: 1.31, 1.71).

CONCLUSIONS: We observed a significant decrease in the frequency of first episode genital HSV-2 and a stable number of first episode genital HSV-1 infections in an STD clinic over the last 2 decades.