My partner tested positive for herpes simplex virus type 1 (HSV‑1); how can I minimize my risk of infection, should I get HSV serology, and what preventive measures or treatment should I consider?

Managing HSV-1 Exposure from an Infected Partner

If your partner has HSV-1, you should consider HSV type-specific serology testing to determine if you are already infected, and if seronegative, your partner should be offered daily suppressive antiviral therapy (valacyclovir 500 mg once daily) to reduce transmission risk by approximately 48-50%, combined with consistent condom use and avoidance of sexual contact during any prodromal symptoms or visible lesions. 1, 2

Should You Get Tested?

HSV serology is recommended for persons at increased epidemiologic risk, which explicitly includes sexual partners of someone with known HSV infection. 1

• Type-specific serologic testing using glycoprotein G-based assays can determine if you already have HSV-1 or HSV-2 antibodies 3
• Testing is most valuable when you have no current symptoms, as it establishes your baseline infection status and guides counseling 4
• If you test HSV-1 positive, you already have the infection (likely oral) and cannot be "reinfected" with the same type, though you should still receive counseling about transmission to others 1
• If you test HSV-1 negative, you are susceptible and should implement aggressive prevention strategies 1

Important Testing Caveats

• False positives occur with commercially available tests, particularly at lower index values; results with index values <3.0 should ideally be confirmed with a second method 1
• Approximately 47.8% of US adults aged 14-49 already have HSV-1 antibodies, so there is a reasonable chance you are already seropositive 2
• The test distinguishes HSV-1 from HSV-2, which is critical since they have different natural histories and transmission patterns 1

Risk Reduction Strategies

If You Test HSV-1 Negative (Susceptible)

Your infected partner should be offered daily suppressive antiviral therapy, which is the single most effective intervention for reducing transmission. 1, 2

• Valacyclovir 500 mg once daily reduces HSV-2 transmission by 48-50% in heterosexual couples; the same dosing is recommended for HSV-1, though studied less comprehensively 1, 2
• Suppressive therapy reduces asymptomatic viral shedding from 10.8% of days to 2.9% of days 2
• This medication must be taken daily, not episodically, as episodic treatment does not reduce transmission risk 2

Behavioral Modifications Are Essential

• Avoid all sexual contact (including oral sex) when your partner has any visible lesions or prodromal symptoms (tingling, burning, itching that precedes visible lesions) 1, 2
• Understand that most HSV transmission occurs during asymptomatic periods when no lesions are visible—this is the primary mode of spread and cannot be completely prevented 1, 2
• Consistent latex condom use provides additional protection but does not eliminate risk, as HSV can be transmitted from skin not covered by the condom 2

Understanding HSV-1 Transmission Routes

• HSV-1 is increasingly recognized as a cause of genital herpes, with 5-30% of first-episode genital herpes caused by HSV-1 1, 5
• Oral HSV-1 can be transmitted to the genitals through oral-genital contact (fellatio or cunnilingus) 2
• HSV-1 genital infections have significantly fewer recurrences and less viral shedding compared to HSV-2 genital infections 6
• Most HSV-1 infections (74%) occur without recognized symptoms, meaning your partner may shed virus without knowing it 5

Critical Counseling Points

What Your Partner Needs to Know

• Your partner should receive comprehensive counseling about the natural history of HSV-1, including the potential for asymptomatic viral shedding and sexual transmission 1, 6
• If your partner has symptomatic genital HSV-1, treatment with antivirals (valacyclovir 1 g twice daily for 7-10 days for first episode, or 500 mg twice daily for 5 days for recurrences) controls symptoms but does not eliminate latent virus 1, 6
• Suppressive therapy for genital HSV-1 is generally not recommended unless recurrences are frequent, as HSV-1 recurs much less often than HSV-2 6

For Both Partners

• Both of you must understand that transmission can occur even with suppressive therapy and condoms—no strategy eliminates risk entirely 2
• HSV-1 establishes lifelong latent infection that antivirals control but do not eradicate 6
• If you are a woman of childbearing age and become infected, you must inform obstetric providers during any pregnancy due to risk of neonatal infection 1, 2

Common Pitfalls to Avoid

• Do not rely solely on avoiding sex during visible outbreaks—the majority of transmission occurs during asymptomatic periods 1, 2
• Do not assume episodic treatment in your partner reduces your transmission risk—only daily suppressive therapy has this effect 2
• Do not use topical acyclovir—it is substantially less effective than oral systemic therapy 1
• Do not assume condoms alone provide complete protection—they reduce but do not eliminate transmission risk 2

Special Considerations

• The rate of HSV-1 acquisition (2.5 per 100 person-years) is now more than twice that of HSV-2 (1.1 per 100 person-years) in young women 5
• Younger individuals (18-22 years) are more likely to acquire HSV-1 infections 5
• There are no clinical differences between genital HSV-1 and genital HSV-2 disease during acute episodes, but long-term prognosis differs significantly 5