Herpes simplex virus (HSV), which includes both HSV-1 and HSV-2, is a common viral infection that stays with an infected person for life. The virus is known for causing periodic outbreaks of blisters or sores, but it is often present without any outward signs. A central concern is the risk of transmitting it to a partner when no symptoms are visible, a period commonly referred to as when the virus is “dormant.” Understanding the true state of the virus during these symptom-free periods is necessary to clarify how transmission can still occur.
Understanding Viral Latency
When the virus is described as dormant, it is technically in a state called latency, which is a key part of the herpes simplex virus life cycle. After the initial infection, the viral particles travel along sensory nerves to a cluster of nerve cells known as a ganglion. For genital herpes (typically HSV-2), this is usually the sacral ganglia near the base of the spine, while oral herpes (typically HSV-1) often resides in the trigeminal ganglia near the skull.
In this latent state, the virus is largely inactive, meaning it is not replicating and causing visible disease symptoms. The virus’s genetic material remains hidden within the nerve cell nucleus, waiting for a trigger to reactivate. This biological arrangement explains why the infection is considered lifelong, as the virus can never be completely eliminated from the body. The latent phase is distinct from a clinical outbreak, which involves the virus traveling back to the skin surface.
The Reality of Asymptomatic Shedding
Despite the virus being in a latent state, transmission can and frequently does occur when no sores or symptoms are present. This phenomenon is called asymptomatic viral shedding, which is the mechanism by which the virus silently spreads. During shedding, the virus briefly reactivates in the nerve endings and travels back to the skin or mucosal surface without causing a noticeable lesion.
The virus is then released in small amounts in bodily secretions or through the surface of seemingly healthy skin or mucous membranes. Most new herpes infections are transmitted during these periods of asymptomatic shedding, often by individuals who do not even know they have the infection. Studies have shown that viral shedding occurs on a significant percentage of days, even in people with very mild or no symptoms.
For individuals with HSV-2, shedding occurs on approximately 20% of days, meaning the virus is intermittently present on the skin surface. This shedding period is typically short, with about 75% of asymptomatic shedding events lasting only a single day. The presence of the virus on the skin, even without visible blisters, makes direct skin-to-skin contact an effective route for transmission.
Factors That Influence Transmission Risk
The likelihood of viral shedding and subsequent transmission fluctuates based on several biological and behavioral factors. The type of herpes simplex virus significantly influences shedding frequency; genital HSV-2 is associated with much more frequent asymptomatic shedding than genital HSV-1. Additionally, the time since the initial infection plays a role, as viral shedding is generally more frequent during the first year after a person contracts the virus and tends to decrease over time.
A person’s overall immune status can also affect the frequency with which the virus reactivates and sheds. Factors that temporarily weaken the immune system, such as emotional stress, concurrent illness, fever, or immune suppression, can increase the chances of viral reactivation and shedding. The risk of transmission is also higher from a male source partner to a female partner than the reverse.
Furthermore, the type of sexual contact is relevant, with skin-to-skin contact and mucosal exposure being the primary routes for viral transfer. While the risk of transmission is highest during a symptomatic outbreak, the frequency of asymptomatic shedding events means they account for the majority of new infections.
Minimizing Transmission Risk
Proactive strategies can be employed to significantly lower the risk of transmitting the herpes simplex virus during periods when it is dormant. Consistent and correct use of barrier protection, such as latex or polyurethane condoms and dental dams, helps reduce direct contact with the areas where viral shedding may occur. Barrier methods reduce the risk but do not eliminate it entirely, as they do not cover all potential areas of viral presence.
The most effective medical intervention to minimize risk during asymptomatic periods is the use of daily suppressive antiviral therapy. Medications like valacyclovir and acyclovir, when taken daily, work to reduce the frequency and duration of asymptomatic viral shedding. Clinical trials have shown that this suppressive therapy can reduce the frequency of viral shedding by 76% to 82%.
For heterosexual couples where one partner has HSV-2, suppressive valacyclovir has been shown to reduce the risk of transmission to the uninfected partner by nearly half. Open and honest communication with sexual partners about the infection status is a fundamental part of a transmission reduction strategy. Combining barrier protection, disclosure, and daily suppressive medication provides the highest level of risk reduction.