Herpes Simplex
Basics
Description
- Characteristic vesicular rash primarily located in oral and genital regions caused by infection with HSV-1 and HSV-2
- Historically, HSV-1 and HSV-2 caused infection in different areas. HSV-1 in the lips, mouth, face, and eyes and HSV-2 in the genitals. At present, primary genital infection with HSV-1 is as common as with HSV-2.
- Wide range of sequelae, impacted by age and immune status of host, whether the infection is primary or recurrent, and the degree of dissemination
- Viral shedding is typically greatest in the first (primary) infection and lessens with recurrences.
Epidemiology
Affects all ages; most HSV-1 is acquired in childhood, and most HSV-2 is acquired in young–middle adulthood.
Incidence
>1 million new cases of HSV per year
Prevalence
- Widespread; 1–25% of adults may shed HSV-1 or HSV-2. Many are unaware of their infection status.
- HSV-1 about 49% and HSV about 12% (1)
- Prevalence of antibodies to HSV-1 is 90% by adulthood in the general population; 33% of the population infected by age 5 years
- 30% of adults have antibodies to HSV-2.
- According to the WHO, about 417 million people worldwide, ages 15 to 49 years are affected by HSV-1.
- 400 million people have genital herpes caused by HSV-2.
- 1 in 5 pregnant women are seropositive for HSV-2.
Etiology and Pathophysiology
HSV-1 and HSV-2 are double-stranded DNA viruses from the family Herpesviridae. HSV-1 and HSV-2 are transmitted by contact with infected skin during periods of viral shedding. Transmission can occur vertically during childbirth.
Risk Factors
- Immunocompromised state: advanced age, chemotherapy, malignancy, or chronic diseases such as diabetes or AIDS
- Atopic eczema, especially in children
- Sexual intercourse with infected person (Condoms minimize transmission, but lesions outside condom-protected areas can spread virus.)
- Occupational exposure: dental professionals at higher risk for HSV-1 and resulting herpetic whitlow
- Neonatal herpes simplex: usually via vaginal birth; greatest risk with primary genital herpes infection; incubation is usually from 5 to 7 days (rarely 4 weeks); cutaneous, mucous membrane, or ocular signs seen in only 70%
- Herpes gladiatorum: contact with abrasion sites, often acquired through high-contact sports (such as rugby and wrestling)
General Prevention
- If active lesions are present, avoid direct contact with immunocompromised people, elderly, and newborns.
- Hand hygiene
- Avoid kissing, sharing beverages, sharing utensils, and sharing toothbrushes.
- Genital herpes: Avoid sexual contact if active lesions are present (transmission can occur when disease appears inactive); discuss condom benefits and limits, and encourage safe sex; and consider antiviral therapy to reduce viral shedding.
Commonly Associated Conditions
- Erythema multiforme: 50% of cases associated with HSV-1 or HSV-2
- Herpetic whitlow, Bell palsy
- Screen all severe, treatment-resistant, or unusual HSV for concurrent HIV infection.
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Citation
Domino, Frank J., et al., editors. "Herpes Simplex." 5-Minute Clinical Consult, 33rd ed., Wolters Kluwer, 2025. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116274/all/Herpes_Simplex.
Herpes Simplex. In: Domino FJF, Baldor RAR, Golding JJ, et al, eds. 5-Minute Clinical Consult. Wolters Kluwer; 2025. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116274/all/Herpes_Simplex. Accessed December 9, 2024.
Herpes Simplex. (2025). In Domino, F. J., Baldor, R. A., Golding, J., & Stephens, M. B. (Eds.), 5-Minute Clinical Consult (33rd ed.). Wolters Kluwer. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116274/all/Herpes_Simplex
Herpes Simplex [Internet]. In: Domino FJF, Baldor RAR, Golding JJ, Stephens MBM, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2025. [cited 2024 December 09]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116274/all/Herpes_Simplex.
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