A new study has confirmed genital herpes is the most common sexually transmitted infection (STI) in the world that does not have a cure and is lifelong.

The burden on global health is immense. According to the most recent data from 2020, nearly 900 million worldwide are currently living with genital herpes.

That's up to about 24 percent of people under the age of 50 who are impacted by the incurable condition.

Roughly 520 million of this cohort have genital herpes from herpes simplex virus type 2 (HSV-2). Around 376 million have contracted it from an HSV-1 infection.

HSV-1 usually only causes cold sores in and around the mouth, but it can be transmitted via sexual activity and cause genital herpes in people without a previous oral infection.

To put the numbers on genital herpes in perspective, the World Health Organization (WHO) reported 129 million new cases of chlamydia in 2020, which is another highly common STI.

But chlamydia is curable. Herpes is not, which means that a case contracted in 2020 can still be a problem years down the road.

"New prevention and treatment measures… are needed critically to control HSV infections and reduce the associated disease burden," conclude the authors of the analysis, led by epidemiologist Manale Harfouche from the Weill Cornell Medicine-Qatar, a branch of Cornell University.

The estimates were supported and commissioned by WHO as part of a regular surveillance of STI cases worldwide, and while the data is still missing in some parts of the world and for some groups of people, the results suggest genital herpes has a vast and largely neglected impact on global health.

"Not enough has been done to address this common infection," says WHO medical officer Sami Gottlieb, an author of the new report.

Genital herpes can be extremely difficult to diagnose and track, as infections often do not come with any symptoms and wrong results on blood tests are common. Most people are blissfully unaware they carry the super contagious virus, which is spread via contact with sores or bodily fluid.

Others experience pain and discomfort during flare-ups, which can impact their sex life and their mental well-being.

In the current analysis, the estimated number of people under 50 with at least one episode of HSV-attributable genital ulcer disease was 188 million for HSV-2 and 17 million for HSV-1.

That's 205 million people in total who are possibly suffering from genital sores each year.

While antiviral medicine can somewhat treat these recurrent infections, reducing their length and severity, they can't cure the condition, and they don't work for everyone.

Part of the problem is that herpes carries a heavy social stigma that makes the infection particularly difficult to study.

"Herpes can be a devastating disease. But because it's sexually transmitted, people don't want to talk about it," explained immunobiologist Akiko Iwasaki from Yale University in 2023.

Iwasaki is one of several scientists who have tested possible herpes vaccines, but they say research has stalled due to a lack of investment.

"People used to email me all the time asking when a vaccine would be available, saying their lives had been destroyed by the virus. But without interest from pharmaceutical companies, we can't go any farther," explained Iwasaki in a press release for the Yale School of Medicine last year.

Beyond the pain and discomfort wrought by genital ulcers, the viral infection can also raise the risk of contracting human immunodeficiency virus ( HIV), and it can put the lives of newborns at risk.

Recent evidence suggests the virus might even contribute to dementia later in life if the infection spreads inside the brain.

Nevertheless, Harfouche and colleagues say that "hardly any specific programs for HSV prevention and control exist, even in resource-rich countries, partly due to the lack of tools to address such highly prevalent, often asymptomatic, and incurable infections on a population level."

Available treatments and screening tests, the authors say, have only had a "modest" impact on incidence rates, at best.

Herpes is an STI not going anywhere anytime soon.

The study was published in BMJ.