Increasing proportion of herpes simplex virus type 1 among women and men diagnosed with first-episode anogenital herpes: a retrospective observational study over 14 years in Melbourne, Australia

Abstract

ObjectivesReports of rising herpes simplex virus type 1 (HSV-1) genital infections relative to HSV-2 have been published up to 2006 in Australia. These changes have been attributed to declining childhood immunity to HSV-1. We described the temporal trends of HSV-1 and HSV-2 up to 2017 in Melbourne, Australia, to determine if the earlier trend is continuing.MethodsWe conducted a retrospective review of the medical records of 4517 patients who were diagnosed with first episode of anogenital HSV infection at the Melbourne Sexual Health Centre, Australia, between January 2004 and December 2017. HSV-1 and HSV-2 were calculated as a proportion of all first episode of anogenital HSV infections. The change in the proportions of HSV-1 and HSV-2 over time was assessed by a χ2 trend test. Risk factors associated with HSV-1 were examined using a multivariable logistic regression model.ResultsThe proportion of first episode of anogenital herpes due to HSV-1 increased significantly over time in women (from 45% to 61%; ptrend<0.001) and heterosexual men (from 38% to 41%; ptrend=0.01) but not in men who have sex with men (MSM) (ptrend=0.21). After adjusting for condom use, partner number and age, the annual increase remained significant only in women (OR 1.08, 95% CI 1.03 to 1.13, p<0.001). In MSM, HSV-1 caused up to two-thirds of anogenital herpes in most years and HSV-1 was more likely to be diagnosed at an anal site than genital site (OR 1.69, 95% CI 1.23 to 2.32, p<0.001). Younger age (<28 years) was an independent risk factor for HSV-1 in all groups.ConclusionsThe proportion of first-episode anogenital herpes due to HSV-1 has been rising in women since 2004. HSV-1 has become the leading cause of anogenital herpes in younger populations, women and MSM.

Herpes Simplex Virus Type 1 Interactions with the Interferon System

“…Primary infections of HSV-1 are usually established in the oral mucosa, and less frequently in the genital mucosa or other epithelial surfaces at the periphery. While HSV-2 is the main causative agent of genital herpes overall, the main cause of initial genital herpes is HSV-1 in populations such as young women [ 7 , 8 , 9 , 10 ]. Following infection and replication in stratified squamous epithelial cells, the virus infects innervating sensory nerves in the epidermis and undergoes retrograde axonal transport to the cell body.…”

The global and regional burden of genital ulcer disease due to herpes simplex virus: a natural history modelling study

“…We estimated that in 2016, 491 million people aged 15–49 years had HSV-2 infection, which is almost all sexually transmitted 2. HSV-1, although predominately an oral infection, is increasing as a cause of genital herpes in some settings 3–5. We estimated that 192 million people had genital HSV-1 infection in 2016 2.…”

An Updated Overview of Herpes Simplex Virus-1 Infection: Insights from Origin to Mitigation Measures

“…In a nationwide study in 1999-2000, which showed 76% of the population carrying HSV1 that differed based on age, race, gender [103] Another study indicated the increasing seroprevalence of HSV-1 as in a study combining 25,372 subjects during 1980 and 2003, 15.8% of tested patients were found positive for HSV-1 in 1980, however, 34.9% were positive in 2003 [104]. Meanwhile in a recent, HSV-1 infection prevalence seems to be higher in female population as a 16% increasal has occured in 2017 compared to the 45% female HSV-1 patients observed in the 2004 data obtained from Melbourne Sexual Health Center, Australia [105].…”