21 August 2019
Qatari model forecasts herpes trends in the US
Published online 21 March 2019
The version of the herpes virus most commonly known for causing cold sores around the mouth will lead to more genital infections in the coming years.
A new mathematical model developed in Qatar indicates that herpes simplex virus type 1 (HSV-1) is undergoing a subtle transition in the United States, with declining rates of oral infection in children and rising genital acquisition in young adults.
Often referred to as oral herpes, HSV-1 infection is life-long, highly contagious and leads to the development of cold sores around the mouth as a result of oral transmission during childhood. Recently, however, this virus is also earning its status as a key sexually transmitted infection, alongside HSV-2, the version of the virus more commonly associated with genital herpes.
Researchers at Qatar University and Weill Cornell Medicine-Qatar have modelled the epidemiology of this viral infection until 2100. The model considers the four transmission modes (oral-to-oral, oral-to-genital, genital-to-oral and genital-to-genital), and was fitted to the HSV-1 data of the US National Health and Nutrition Examination Survey, for the period 1976-2016, and the United Nations’ demographic growth prospects.
The model predicts that the number of new infections will persist at around three million per year, while the fraction of the US population that comes in contact with the virus will decline with time. Oral herpes will remain the dominant form of infection, and oral-to-genital transmission (oral sex) the most frequent cause of genital herpes. Close to 500,000 new cases per year will be genital, with a quarter of them being accompanied by clinical manifestations. 25% of all new HSV-1 infections will lead to genital herpes, the prevalence of which is forecast to reach its height around 2060, and then slowly decrease. People aged 15 to 49 will be the most affected by the virus.
“This is one of the best modelling studies I have seen on the transmission dynamics of HSV in a population,” says Abba Gumel, professor of mathematics at Arizona State University, USA, who was not involved in the study. “The authors developed a novel deterministic model that incorporates all the essential life history features of the disease, including age structure, disease transmission by asymptomatic and symptomatic infected individuals, oral and genital modes of acquisition and transmission, and risk structure.”
“We aim to apply the model to other regions in order to characterize the level and trend of the HSV-1 epidemiological transition globally,” say the study’s corresponding authors.
The team is also interested in using mathematical modelling to assess the potential impact of an HSV-1 vaccine. “These findings highlight the need for a vaccine with dual protection against HSV-1 and HSV-2, and should impact public health messaging to young people regarding the risks of sexually transmitted disease spread through oral sex,” says Joshua T. Schiffer of the Fred Hutchinson Cancer Research Center, USA, who was also not involved in the study.
Ayoub, H. H. et al. Characterizing the transitioning epidemiology of herpes simplex virus type 1 in the USA: model-based predictions. BMC Med 17:57 (2019).