Is Asymptomatic Genital Herpes Contagious to Partners?
Yes, asymptomatic genital herpes is absolutely contagious to sexual partners, and transmission frequently occurs during periods without visible lesions through asymptomatic viral shedding. 1, 2, 3
Understanding Asymptomatic Transmission Risk
Asymptomatic viral shedding is the primary mode of HSV-2 transmission and occurs frequently even when no symptoms are present. 4, 2 This is a critical concept that many patients and providers underestimate:
- Approximately 20% of HSV-2 seropositive persons remain completely asymptomatic throughout their infection, yet they can still transmit the virus 1, 4
- Many cases of genital herpes are acquired from persons who either don't know they have the infection or were asymptomatic at the time of sexual contact 1
- Genital herpes is frequently transmitted in the absence of symptoms through asymptomatic viral shedding 2, 5
Quantifying the Risk
The annual transmission risk from an infected partner to an uninfected partner in heterosexual couples is approximately 10% without any intervention 6. However, this risk can be substantially reduced through specific strategies.
Evidence-Based Prevention Strategies
Suppressive Antiviral Therapy
Suppressive antiviral therapy with valacyclovir 500 mg once daily reduces HSV-2 transmission to susceptible heterosexual partners by 48-50%. 4 This is the most effective pharmacologic intervention:
- The mechanism works by suppressing viral shedding, not by eliminating it completely 1, 4
- This approach should be offered to serodiscordant couples (where one partner is HSV-2 positive and the other is negative) 4
- Suppressive therapy does NOT eliminate transmission risk entirely—it reduces but does not prevent all viral shedding 1, 4
Critical Exception for HIV Coinfection
Suppressive therapy is NOT effective for reducing transmission in HIV/HSV-2 coinfected individuals. 1, 4 This is an important pitfall to avoid when counseling patients.
Barrier Protection
- Condom use during all sexual activities that pose transmission risk is strongly encouraged 4
- Condoms provide additional protection but do not eliminate risk, as HSV can be transmitted from areas not covered by condoms 3
Behavioral Modifications
- Avoiding sexual activity when lesions are present is recommended, but this alone is insufficient since most transmission occurs during asymptomatic periods 4, 2
- Patients should be taught to recognize early prodromal symptoms (tingling, itching, burning) that may precede visible lesions 4
Essential Patient Counseling
Every asymptomatic HSV-2 positive patient must receive comprehensive education about transmission risk. 4 This counseling should include:
- The potential for recurrent episodes, even if they've never had symptoms 4
- That asymptomatic viral shedding occurs frequently and is the primary mode of transmission 4, 2
- That sexual transmission occurs during periods without visible lesions in many cases 4
- That suppressive therapy reduces but does not eliminate transmission risk 4
Partner Management
- Sexual partners of infected persons should be advised that they might be infected even if they have no symptoms 2
- Type-specific serologic testing of asymptomatic partners can determine whether risk for HSV-2 acquisition exists 2
- HSV-2 seronegative partners should consider having type-specific serology testing before initiating sexual activity 4
Common Pitfalls to Avoid
- Never assume that absence of symptoms means absence of contagiousness—this is the most dangerous misconception 1, 2, 3
- Do not prescribe suppressive therapy to HIV/HSV-2 coinfected individuals for transmission prevention purposes, as it is ineffective 1, 4
- Do not rely solely on avoiding sex during outbreaks, as this strategy misses the majority of transmission events 4, 2