Around 1 in 5 of the world’s under 50s living with genital herpes (HSV)

Around 1 in 5 of the world’s under 50s—846 million people—are living with genital herpes infection, suggest the latest global estimates, published online in the journal Sexually Transmitted Infections.

And more than 200 million 15-49 year olds probably had at least one symptomatic outbreak of the infection in 2020, the latest year for which figures are available, the data analysis suggests.

The findings prompt the researchers to call for the development of new treatments and vaccines to control the spread of the infection and lessen its health and financial toll, given that currently available options have only had a modest impact at the population level, they say.

There are 2 types of herpes simplex virus—type 1 (HSV-1) and type 2 (HSV-2)--both of which are highly infectious, incurable, and last a lifetime. 

HSV-1 is primarily spread in childhood by mouth contact, resulting in ‘cold sores’ in or around the mouth. But it can sometimes cause more serious neurological, eye, skin and mucous membrane complications. And it is increasingly being spread through sexual contact at older ages, say the researchers. 

HSV-2 is almost entirely sexually transmitted through skin to skin contact, and is the leading cause of recurrent painful genital blisters. And although rare, both HSV-1 and HSV-2 can be passed onto newborns, often proving fatal. 

In a bid to update previous estimates of the global incidence and prevalence of genital HSV infection, the researchers incorporated a series of recent comprehensive systematic reviews and pooled data analyses published up to March 2022

And they deployed mathematical modelling to estimate the global and regional incidence and prevalence of genital HSV infection and related symptoms in 2020.

Based on the available data, the researchers estimated that globally 26 million 15–49 year olds were newly infected with HSV-2 infection, and an estimated 520 million had existing infection—just over 13% of those in this age group.

An estimated 17 million 15–49 year olds acquired HSV-1 infection genitally, and an estimated 376 million (10% of those in this age group) had existing infection in 2020. 

In all, two-thirds of the global population up to the age of 49—-nearly 4 billion people—-were infected (mostly orally) with HSV-1 in 2020, the researchers estimated.

The researchers estimated that the total global numbers of new and existing HSV infections among 15–49 year olds in 2020 were 42 million and 846 million, respectively.

And the estimated number of 15–49 year olds who had at least one episode of genital sores in 2020 was 188 million for those infected with HSV-2, and 17 million for those infected with genital HSV-1, adding up to a total of 205 million.

The researchers acknowledge various limitations to their findings, including the scarcity of data for people at either end of the age spectrum and relatively wide ranges for some of their estimates.

But they nevertheless conclude: “HSV infections are widely prevalent in all global regions, leading to a significant burden of [genital ulcer disease] with repercussions on psychosocial, sexual, and reproductive health, neonatal transmission, and HIV transmission. However, hardly any specific programmes for HSV prevention and control exist, even in resource-rich countries.”

They add: “There is a need for HSV prophylactic and therapeutic vaccines as a strategic approach to control transmission and to curb the disease and economic burdens of these infections.”