The herpes simplex virus type 2 (HSV-2) is a viral infection that causes genital herpes. It establishes a lifelong presence within the host’s nerve cells after initial exposure. While herpes simplex virus type 1 (HSV-1) is often associated with oral cold sores, it can also cause genital infection, but HSV-2 is the dominant cause of recurrent genital outbreaks. Once acquired, the virus enters a dormant or latent stage at the base of the spine. The infection is not curable, but it is manageable through medical and behavioral strategies.
How the Virus is Transmitted
HSV-2 is spread through direct skin-to-skin contact, typically during sexual activity, including vaginal, anal, or oral sex. Transmission occurs when the virus contacts mucous membranes or small breaks in the skin. Condoms reduce the risk, but the virus can still be shed from uncovered areas, such as the upper thighs or buttocks.
A significant portion of transmission occurs during asymptomatic shedding, when the infected person has no visible lesions or symptoms. During these periods, the virus is still present on the skin’s surface and can be passed to a partner. Most genital herpes infections are transmitted by individuals who are unaware they have the infection or who are asymptomatic at the time of contact.
Mother-to-child transmission during childbirth is a serious risk factor, leading to neonatal herpes. The risk is greatest when a mother acquires the infection late in pregnancy, before producing protective antibodies for the fetus. This condition is rare, but it can result in severe neurological disability or death for the newborn. To mitigate this risk, antiviral therapy is often prescribed late in pregnancy, and a Caesarean section may be performed if active lesions are present at delivery.
Recognizing Symptoms and Outbreaks
The primary outbreak typically occurs within two to twelve days after exposure and can last two to four weeks. It may be accompanied by systemic symptoms such as fever, headache, muscle aches, and swollen lymph nodes in the groin. The physical manifestation begins with a cluster of small, red bumps that progress into fluid-filled blisters on the genitals, anus, buttocks, or upper thighs.
A milder warning stage, known as the prodrome, precedes both primary and recurrent outbreaks. This stage involves localized sensations such as tingling, itching, burning, or shooting pains where the lesions will appear. Recognizing the prodrome allows an individual to begin episodic treatment early, which can lessen the severity and duration of the outbreak.
Following the blister stage, the lesions rupture and become painful, open ulcers that may ooze fluid. These ulcers eventually crust over and heal without scarring, marking the end of the active outbreak. Recurrent outbreaks are usually milder and shorter than the primary episode because the body has developed an immune response.
Triggers for recurrence vary but can include emotional stress, illness, friction, and hormonal changes like menstruation. Over time, the frequency and severity of recurrent episodes tend to decrease. HSV-2 is much more likely than genital HSV-1 to cause frequent recurrences. However, many people infected with HSV-2 experience no symptoms or have such mild symptoms that they are mistaken for insect bites or abrasions.
Confirming the Diagnosis
Diagnosis relies on two main types of laboratory tests: viral detection and antibody testing. For individuals with active sores, the preferred method is a swab taken from the lesion for a viral culture or a polymerase chain reaction (PCR) test. PCR testing is highly sensitive because it detects viral DNA, often yielding results within 24 hours.
Viral culture is less sensitive than PCR, especially as lesions heal and viral load decreases. A negative result from a viral culture or PCR test does not entirely rule out infection, particularly if the sample was taken from an older lesion. For individuals without active lesions, or for general screening, a blood test for antibodies is used.
This serology test looks for immunoglobulin G (IgG) antibodies, which the immune system creates in response to the virus. IgG testing is type-specific, differentiating between HSV-1 and HSV-2, which is important for counseling on prognosis and transmission risk. A limitation is the waiting period, as it takes several weeks after initial exposure for the body to develop detectable antibodies. Testing for immunoglobulin M (IgM) antibodies is generally not recommended because it is not reliably type-specific and offers little value in diagnosing a new infection.
Treatment and Long-Term Management
While there is no cure for HSV-2, antiviral medications effectively manage symptoms and reduce the frequency of outbreaks and the risk of transmission. The three commonly prescribed antiviral agents are acyclovir, valacyclovir, and famciclovir. These drugs work by interfering with the virus’s ability to replicate, slowing its spread in the body.
Treatment is divided into two strategies: episodic therapy and suppressive therapy. Episodic therapy involves taking a short course of medication, typically for one to five days, at the first sign of an outbreak or the prodrome stage. This approach accelerates healing and reduces the severity and duration of active lesions.
Suppressive therapy involves taking a low-dose antiviral medication daily on a long-term basis. This daily regimen is highly effective, reducing the frequency of symptomatic recurrences by 70 to 80% for people with frequent outbreaks. Suppressive therapy also reduces the risk of transmission to a sexual partner, decreasing the rate of HSV-2 transmission in discordant heterosexual couples.
Management also involves behavioral adjustments focused on reducing transmission risk. Individuals are advised to abstain from sexual activity when symptoms or lesions are present, as viral shedding is highest during an active outbreak. Open disclosure of HSV-2 status to a partner is fundamental, alongside the consistent use of barrier methods like condoms. Combining suppressive therapy with consistent condom use and avoiding sexual contact during outbreaks offers the most comprehensive strategy for reducing transmission.