Infection with the herpes simplex virus, commonly known as herpes, can be due to either herpes simplex virus type 1 (HSV-1) or herpes simplex virus type 2 (HSV-2). HSV-1 is mainly transmitted by oral to oral contact and cause infection in or around the mouth (oral herpes). HSV-2 is almost exclusively sexually transmitted, causing infection in the genital or anal area (genital herpes). However, HSV-1 can also be transmitted to the genital area through oral-genital contact to cause genital herpes. In rare circumstances, genital herpes can be spread from a mother to her infant during birth.

Most genital herpes infections are asymptomatic or can have mild symptoms that go unrecognized. In 10-25% of primary infections, genital herpes is characterized by one or more genital or anal blisters or ulcers, usually 4-7 days after sexual exposure. Symptomatic genital HSV is a lifelong condition that can be characterized by frequent symptomatic recurrences. Genital herpes infection is often diagnosed clinically. However, laboratory testing is required to differentiate between HSV-1 and HSV-2. When vesicles are not present, laboratory confirmation may also be needed to rule out other causes of genital ulcers. Currently there is no cure or vaccines for herpes. Antiviral medications are the most effective treatments available for people infected with genital herpes. These can help to reduce the severity and frequency of symptoms but cannot cure the infection.

HSV-2 infection is the most common cause of recurrent genital ulcer disease (GUD) worldwide. Additionally, HSV-2 infection is of particular concern due to its epidemiological synergy with HIV infection and transmission. People who are infected with HSV-2 are approximately three times more likely to become infected with HIV, and people with both HIV and genital HSV are more likely to transmit HIV to others. HSV-2 is often transmitted by people who are unaware of their infection or who are asymptomatic at the time of sexual contact.

Key Facts

  • An estimated 19.2 million new HSV-2 infections occurred among adults and adolescents aged 15–49 years worldwide in 2012, with the highest rates among younger age groups
  • HSV-2 is a lifelong infection; the estimated global HSV-2 prevalence of 11.3% translates into an estimated 417 million people with the infection in 2012
  • In 2012, there were 2.2 million new cases of HSV-2 infections among females, and 1.3 million new cases among men in the Region of the Americas
  • In 2012, there were 45.2 million exiting cases of HSV-2 infection in females, and 25.1 million existing cases of HSV-2 infections in men in the Region of the Americas

PAHO/WHO response

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