HSV-1 Genital Herpes: Clinical and Epidemiological Considerations

Introduction to HSV-1 Genital Herpes

Changing sexual practices, particularly increased oro-genital contact, directly transmit HSV-1 from oral sites to genital mucosa, according to the Eurosurveillance guideline 1
The initial clinical presentation of genital HSV-1 is indistinguishable from HSV-2, making laboratory typing essential for accurate prognosis, as recommended by the MMWR Recommendations and Reports guideline 2

Viral typing should be performed on all genital herpes isolates because the natural history and recurrence patterns differ substantially between HSV-1 and HSV-2, as suggested by the MMWR Recommendations and Reports guideline 2
Type-specific serologic testing can distinguish HSV-1 from HSV-2 antibodies and is useful for diagnosing unrecognized infections, according to the Annals of Internal Medicine guideline 3

Most genital herpes infections (80-90%) progress subclinically, yet transmission occurs during asymptomatic viral shedding, as reported in Eurosurveillance 1
The stigma associated with HSV-2 is greater than HSV-1 because HSV-2 is almost exclusively sexually transmitted, while HSV-1 can be acquired through non-sexual contact, according to Eurosurveillance 1

Herpes Simplex Virus Type 1 (HSV-1) primarily causes orolabial disease, though it increasingly causes genital herpes through oro-genital contact, according to the Centers for Disease Control and Prevention (CDC) 4, 5
Herpes Simplex Virus Type 2 (HSV-2) nearly exclusively causes genital disease and is almost always sexually transmitted, as reported by the American College of Obstetricians and Gynecologists (ACOG) 4, 5

HSV-1 traditionally manifests above the neck, acquired through close contact, affecting the oro-pharynx, mouth, lips, chin, and occasionally eyes, as noted by the World Health Organization (WHO) 6, 7
HSV-2 traditionally manifests below the waist, acquired through sexual contact later in life, affecting genital mucosa, genital skin, and perigenital regions, according to the CDC 6, 7

In the United States (2015-2016), 47.8% of the population aged 14-49 years is seropositive for HSV-1 and 12.1% for HSV-2, as reported by the National Institutes of Health (NIH) 4, 5
HSV-1 seroprevalence reflects both oral and genital infection, as noted by the American Academy of Pediatrics (AAP) 4, 5

The 12-month recurrence rates are 55% for genital HSV-1 compared to 90% for genital HSV-2, highlighting the importance of viral typing in clinical management 8
Episodes of genital HSV-1 infection are indistinguishable from genital HSV-2 infection clinically, but genital HSV-1 recurs less frequently, emphasizing the need for laboratory confirmation 9
PCR from genital lesions is the most sensitive method for confirming HSV infection and should include viral typing, as recommended by infectious disease guidelines 8
Type-specific serologic assays based on glycoprotein G can distinguish HSV-1 from HSV-2 antibodies and are useful for diagnosing unrecognized infections, according to the American College of Physicians 10

PCR is the preferred diagnostic method, especially for suboptimal collection or nonulcerative/vesicular lesions, due to its high sensitivity 8
Viral culture is more likely positive in vesicular versus ulcerative lesions and in first episodes versus recurrent lesions, although PCR is generally preferred 8
The Centers for Disease Control and Prevention recommends using glycoprotein G-based assays for type-specific serologic testing to accurately distinguish HSV-1 from HSV-2 9