Description

• Characteristic vesicular rash primarily located in oral and genital regions caused by infection with:
  • HSV-1: blisters mostly on lips, in mouth, face, eyes
  • HSV-2: blisters primarily on the genitals
• Historically, HSV-1 and HSV-2 caused infection in different areas. More recently, the incidence of primary genital infection with HSV-1 is as common as with HSV 2 (HSV-1 can cause genital sores through oral–genital contact).
• Associated with a wide range of sequelae, depending on the 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.
• Meningitis, encephalitis, and pneumonia are serious systemic manifestations associated with HSV infection.

Epidemiology

• Affects all ages; most HSV-1 is acquired in childhood, and most HSV-2 is acquired in young–middle adulthood.
• Predominant sex: male = female

Incidence

• >1 million new cases of HSV per year
• HSV can reactivate, causing recurrent disease.

Prevalence

• Widespread; 1–25% of adults may shed HSV-1 or HSV-2 at any given time. Many are unaware of their infection status.
• 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 World Health Organization, about 417 million people in the world age ranging from 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
• Prior HSV infection
• Sexual intercourse with infected person (Condoms help minimize HSV 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 acquired by vaginal birth to an infected mother; risk is greatest in mothers 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 sports with high levels of physical contact (such as rugby and wrestling)
• People with HSV-2 have a higher risk of developing HIV infection due to open ulcers or lymphocytes at lesions, facilitating HIV invasion during sexual contact.

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 (although 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.