Time Trends in First Episode Genital HSV infections in an Urban STD Clinic

Thesis (Master's)--University of Washington, 2016-06

Background: Genital HSV-1 has emerged as a more common cause of first episode genital herpes in the last few decades. We examined trends in etiology of first episode genital HSV infection in a 21-year period and determined risk factors for genital HSV-1 versus genital HSV-2 infection. Methods: Using an electronic database, we identified persons who visited Public Health – Seattle & King County STD Clinic from 1993 through 2014 with genital ulcers. We selected persons diagnosed with a first episode of culture positive genital HSV. Poisson regression was used to determine risk factors for first episode genital HSV-1 versus HSV-2 infection. Results: Of 52,030 patients with genital ulcers, 3,199 (6.15%) patients had culture-proven first episode genital HSV infection: 1,059 (33.1%) with HSV-1 and 2,140 (67.9%) with HSV-2. Overall, 1,213 (37.9%) patients with first episode genital HSV were women. The median age was 27 (range 13-81) years of age. 1,959 (61.2%) patients were white, and 377 (11.8%) were men who have sex with men. Over time, the number of patients with HSV-2 has declined 6% per year, from 223 in 1993 to 39 in 2014 (RR=0.94 per year, 95% CI=0.93, 0.95) while the number of patients with HSV-1 remained stable at about 50 per year (RR=1.0; 95% CI: 0.99, 1.01), resulting in an increasing proportion attributed to HSV-1 over time, from 16.9% in 1993 to 44% in 2014. Among patients with first-episode genital HSV, age <30 years (RR=1.40; 95% CI: 1.20, 1.63), white race (RR=3.03; 95% CI: 2.37, 3.87), and reporting homosexual practice (RR=1.42; 95% CI: 1.19, 1.71) were associated with genital HSV-1 infection compared with genital HSV-2 infection. Conclusions: We observed a significant decrease in first episode genital HSV-2 in the last 21 years with a stable number of first episode genital HSV-1 infections. Understanding changing epidemiology in genital HSV infection may inform prevention strategies.