Objectives Reports 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.
Methods We 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.
Results The 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.
Conclusions The 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 genitalis
- herpes simplex
- sexual health
- risk factors
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Handling editor Jonathan Ross
Contributors EPFC and CKF conceived and designed the study. DCD, EPFC and CKF undertook the data analysis. DCD wrote the first draft of the manuscript. All authors critically revised the article and approved the final version.
Funding TRHR and EPFC are supported by Early Career Fellowships from the National Health and Medical Research Council (TRHR: 1091536, EPFC: 1091226).
Competing interests Melbourne Sexual Health Centre has received funding from SpeeDx to undertake research studies on Mycoplasma genitalium. The authors of this paper declare no additional conflicts of interest.
Patient consent for publication Not required.
Ethics approval Alfred Hospital Ethics Committee, Melbourne, Australia (No 101/17).
Provenance and peer review Not commissioned; externally peer reviewed.