Patient has genital HSV‑1 infection; how can I explain how they likely acquired it?

How to Explain Genital HSV-1 Acquisition to Your Patient

The most important message is that genital HSV-1 is primarily acquired through oral-genital contact (oral sex) from a partner who has oral HSV-1, and the first visible outbreak does not indicate when infection occurred—it could represent recent acquisition or reactivation of virus acquired months or years ago from any previous partner. 1, 2

Primary Transmission Route: Oral-Genital Contact

• Genital HSV-1 is overwhelmingly acquired through oral sex, with over 85% of genital HSV-1 infections resulting from oral-to-genital transmission rather than genital-to-genital contact 3
• The partner performing oral sex typically has oral HSV-1 (which affects approximately 60% of adults) and may have been completely asymptomatic at the time of transmission 4, 5
• HSV-1 is traditionally associated with oral infections but increasingly causes genital disease due to orogenital sexual practices 1

Critical Timing Concept: First Outbreak ≠ Recent Infection

This is the most important counseling point to prevent relationship distress:

• In 80-90% of cases, genital herpes infection is initially subclinical—meaning the person becomes infected but develops no symptoms at the time of transmission 2
• The virus immediately establishes latency in the sacral ganglia regardless of whether symptoms appear 2
• The first visible outbreak may indicate either recent or long-lasting infection—it could represent reactivation of virus acquired years ago during any previous relationship 2
• These subclinically infected individuals can remain asymptomatic for months, years, or even their entire lifetime before their first outbreak 2

Explaining the Uncertainty of Timing

• It is difficult or impossible to determine exactly when or from whom a person acquired HSV-1 2
• The appearance of symptoms does not prove recent sexual contact or infidelity 2
• Even individuals with only one lifetime sexual partner can have genital herpes 2
• The severity of the first clinical episode does not correlate with timing of acquisition 2

Common Transmission Scenarios to Discuss

Scenario 1: Asymptomatic partner transmission

• Many people acquire genital herpes from partners who don't know they have oral HSV-1 or who were completely asymptomatic during the sexual contact 2
• The transmitting partner may have never had a visible cold sore in their life 4

Scenario 2: Delayed symptom onset

• The patient could have been infected during a previous relationship years ago but is only now experiencing their first visible outbreak 2
• The incubation period ranges from 2-10 days but can extend up to 4 weeks for initial symptoms; however, reactivation can occur at any point thereafter 4

Scenario 3: Current partner with oral HSV-1

• If the current partner has a history of cold sores (or is HSV-1 seropositive), transmission likely occurred through oral sex 1, 3
• Transmission can occur even without visible oral lesions due to asymptomatic viral shedding 2

Key Counseling Pitfalls to Avoid

• Never assume that a first clinical episode indicates recent acquisition or infidelity 2
• Do not suggest that the timing of symptoms correlates with timing of exposure 2
• Avoid implying blame toward any specific partner without serologic testing 2

Optional Diagnostic Clarification

• Type-specific serologic testing can help determine if this is truly a new infection versus reactivation, though it cannot pinpoint exact timing of acquisition 2
• Testing the partner for HSV-1 antibodies may provide context but won't definitively establish transmission source 2

Epidemiologic Context to Share

• HSV-1 seroprevalence is approximately 60% in adults, with most infections acquired through non-sexual contact in childhood 4
• However, genital HSV-1 is increasingly common, with HSV-1 now causing a substantial proportion of first-episode genital herpes, particularly in well-resourced settings 1
• For those aged 15-49 years, nearly 25% of incident HSV-1 infections are genital 3