Background Genital infection with herpes simplex virus type 2 (HSV-2) is the most common cause of genital ulcer disease worldwide and increases susceptibility to, and transmissibility of, HIV. HSV type 1 (HSV-1) can also cause genital herpes, but most HSV-1 infection is oro-labial (“cold sores”) and acquired during childhood. Neonatal herpes, acquired during delivery from mothers with genital herpes, is rare but has high rates of mortality and lifelong disability. The global burden of HSV-2 infection was last estimated for 2003. The global burden of HSV-1 infection, and of neonatal herpes, has never been estimated to our knowledge.
Aim To present, for 2012, new global HSV-2 estimates for females and males aged 15–49 years, first global HSV-1 estimates for females and males aged 0–49 years, and first global estimates of neonatal herpes cases.
Methods Literature review of recent HSV-1 and HSV-2 prevalence studies world-wide, followed by fitting of a model with constant incidence by age to pooled prevalence values by HSV type, WHO region, age and sex. Prevalence values were adjusted for test sensitivity and specificity. Published risks of neonatal herpes transmission were applied to maternal infections to estimate neonatal herpes cases.
Results We estimate that in 2012, 417 million people aged 15–49 years (range: 274–678 million) had existing HSV-2 infection world-wide: a global prevalence of 11.3%. Of those infected, 267 million were women. Also in 2012, we estimate that 19.2 million (range: 13.0–28.6 million) individuals aged 15–49 years were newly-infected with HSV-2: 0.5% of all individuals globally. Prevalence was highest in Africa (31.5%), followed by the Americas (14.4%). Burden of numbers infected was highest in Africa. However, despite lower prevalence, South-East Asia and Western Pacific regions also contributed large numbers to the global totals because of large population sizes. Estimates for HSV-1 and neonatal herpes will be presented at the conference.
Conclusions The global burden of HSV infection is large. This highlights the critical need for development of vaccines, microbicides and other prevention strategies against HSV.