Genital Herpes (HSV-1 & HSV-2): Diagnosis, Treatment & Suppression
Evidence-based clinical guide to genital herpes: HSV-1 vs HSV-2, viral PCR swab diagnosis, episodic antiviral treatment, suppressive therapy, and pregnancy care.
Clinical Presentation: Primary Episode vs Recurrences
The clinical course of genital herpes varies markedly between the initial presentation and subsequent recurrences:
- Primary (First Clinical) Episode: Often severe and systemic. Presents 2 to 14 days after exposure with widespread clusters of painful, fluid-filled vesicles on an erythematous base, which rapidly rupture into tender, shallow ulcers. Accompanied by systemic 'flu-like' symptoms (fever, malaise, myalgias, headache), tender bilateral inguinal lymphadenopathy, and excruciating dysuria (which may precipitate acute urinary retention, especially in young women). Healing takes 2 to 3 weeks without treatment.
- Recurrent Episodes: Typically much milder, more localised, and shorter (lasting 3 to 7 days). Often preceded by a distinct prodrome (focal tingling, itching, burning, or neuralgic ache radiating down the buttocks or back of thighs). Recurrences are significantly more frequent with HSV-2 than with genital HSV-1.
Diagnostic Gold Standard: Viral Swab PCR
Accurate diagnosis requires viral NAAT / PCR swab of the base of an active lesion (blister fluid or fresh ulcer base). PCR differentiates accurately between HSV-1 and HSV-2, which is essential for prognostic counselling regarding future recurrence frequency.
Serology (blood antibody testing) is rarely indicated for acute diagnosis, as it cannot determine the anatomical site of infection or timing of acquisition, and carries high false-positive rates.
Antiviral Management Protocols
Oral antiviral therapy (nucleoside analogues) accelerates lesion healing, blunts pain, and halts viral replication:
- First-Episode Treatment: Valaciclovir 500 mg orally twice daily for 5 to 10 days (or Famciclovir 250 mg three times daily). Commenced as early as possible after clinical suspicion. Supportive care includes oral analgesia, lignocaine 2% gel applied topically, warm salt baths, and voiding in a warm bath if severe dysuria occurs.
- Episodic Treatment for Recurrences: Patient-initiated short-course antiviral therapy taken at the very first sign of the prodromal tingle: e.g. Famciclovir 1000 mg stat, followed by 1000 mg 12 hours later; or Valaciclovir 500 mg twice daily for 3 days.
- Continuous Daily Suppressive Therapy: Indicated for individuals with frequent recurrences (≥ 6 episodes per year), severe psychosocial distress, or to reduce transmission risk to an uninfected partner. Standard regimen: Valaciclovir 500 mg orally once daily. Suppressive therapy reduces recurrence frequency by 70–80% and cuts viral shedding rates by over 50%.
Genital Herpes in Pregnancy
The greatest risk for neonatal herpes (a severe, life-threatening disseminated or CNS infection) occurs when a pregnant woman acquires a primary genital HSV infection in the third trimester, as the foetus is delivered before maternal protective IgG antibodies can be generated and transferred transplacentally. In this setting, elective Caesarean section is strongly recommended.
For women with established recurrent genital herpes prior to pregnancy, the risk of neonatal transmission is very low (< 1%). Oral valaciclovir suppressive therapy is routinely commenced from 36 weeks gestation to suppress viral shedding and prevent active clinical lesions at the time of labour, enabling safe vaginal delivery.