Paper Summary
Methodology
The researchers used a sophisticated mathematical model to estimate the global and regional prevalence and incidence of herpes simplex virus (HSV) infections and genital ulcer disease (GUD) for 2020. They analyzed HSV-1 and HSV-2 infections separately, using a vast collection of data from systematic reviews and meta-analyses across six World Health Organization (WHO) regions. Only studies with validated diagnostic methods were included.
By pooling and calibrating this data with demographic information, the model provided estimates for various age and gender groups. This approach allowed the researchers to update earlier estimates with more precise methods while addressing regional gaps in the available data.
Key Results
The study revealed some staggering numbers about HSV infections in 2020:
About 25.6 million new HSV-2 infections occurred globally among people aged 15–49, with a total of 519.5 million people already living with HSV-2. This means about 13.3% of people in this age range had HSV-2.
For genital HSV-1, there were 16.8 million new infections and 376.2 million people already living with it, equaling about 10.2% prevalence in the same age group.
The combined prevalence of genital HSV-1 and HSV-2 was 846.1 million people worldwide.
The total burden of genital ulcer disease (GUD) episodes caused by HSV was 204.6 million cases, with HSV-2 contributing to the majority.
The African region had the highest rates of HSV infections and GUD, particularly among young adults.
Study Limitations
In some regions, like the Eastern Mediterranean and South-East Asia, there was limited high-quality data, requiring assumptions and pooling from similar regions to fill gaps. HSV diagnostic methods can vary in sensitivity and specificity. Cross-reactivity between HSV-1 and HSV-2 antibodies may have affected the accuracy of some data points.
The model also assumed constant infection rates and relied on demographic data projections, which may not fully capture regional variations in transmission dynamics. The study primarily targeted individuals between ages 15 and 49, leaving some uncertainty about infection dynamics in older or younger populations.
Discussion & Takeaways
The study highlights the significant burden of HSV globally, with millions of people affected by genital infections and associated diseases like GUD. HSV-2 continues to be a major driver of sexually transmitted infections, while HSV-1 is increasingly being transmitted sexually among adults in high-income countries. The researchers emphasize the urgent need for better prevention measures, including vaccines, to reduce the global disease burden.
Additionally, greater public awareness and improvements in STI services could help curb the spread of these infections. The findings are critical for guiding future research, resource allocation, and policy development in sexual and reproductive health.
Funding & Disclosures
This study was funded by the World Health Organization (WHO) through a grant from USAID as part of its Global HIV, Hepatitis, and STIs Programmes. Additional funding was provided by the Qatar Research, Development, and Innovation Council, and the Qatar National Research Fund, as well as the NIHR Health Protection Research Unit at the University of Bristol in partnership with the UK Health Security Agency.
The authors disclosed no competing interests and noted that the views expressed in this article are solely their responsibility and do not necessarily reflect the policies or decisions of their affiliated institutions, including WHO.