Herpes is classified as an infection caused by the herpes simplex virus (HSV), and it can produce disease when it causes symptoms. The distinction matters: most people carrying HSV never develop noticeable illness, so medically, herpes is an infectious condition that sometimes manifests as a clinical disease. With an estimated 3.8 billion people worldwide carrying HSV-1 and another 520 million carrying HSV-2, it is one of the most common infections on the planet.
Infection vs. Disease: Why the Distinction Matters
In medical terms, an infection means a virus has entered your body and established itself. A disease means that infection is actively causing symptoms or damage. Herpes straddles both categories. After the initial exposure, HSV travels along nerve fibers to clusters of nerve cells near the spine or base of the skull, where it essentially goes dormant. During this dormant phase, you’re infected but not diseased. The virus’s roughly 80 genes needed for active replication are silenced, and only a small region of its genetic material remains active, producing what’s called the latency-associated transcript.
This dormancy can last weeks, months, years, or a lifetime. The virus maintains this quiet state through active signals from the nerve cell itself, which continuously suppress the virus’s ability to “wake up.” When those signals are disrupted, whether by stress, illness, immune suppression, or other triggers, the virus reactivates. It travels back along the nerve fibers to the skin surface, where it can cause sores, blisters, or other symptoms. That’s when infection becomes disease.
Of the 520 million people aged 15 to 49 with genital HSV-2 infection globally, only about 205 million experienced even one symptomatic episode in 2020. Roughly 60% of carriers had no noticeable symptoms at all.
The Two Types of Herpes Simplex
HSV-1 primarily causes oral herpes, the cold sores that appear on or around the lips. About 64% of people under 50 worldwide carry it. HSV-1 can also cause genital infections, and an estimated 376 million genital HSV-1 infections exist among 15- to 49-year-olds. HSV-2 is the more common cause of genital herpes, which is classified as a sexually transmitted infection. Both types follow the same biological pattern of infection, dormancy, and potential reactivation.
What a Primary Outbreak Looks Like
If herpes does cause symptoms, the first episode (called a primary infection) is typically the most intense. The incubation period ranges from 1 to 26 days after exposure, though 6 to 8 days is most common. During a primary outbreak, you may notice clusters of small blisters or open sores around the mouth or genitals, along with tingling, itching, or burning. Some people also develop flu-like symptoms including fever, body aches, and swollen lymph nodes.
After the primary episode resolves, the virus retreats into the nerve cells and enters latency. Recurrent outbreaks, if they happen, tend to be shorter and less severe than the first. The frequency of recurrences varies enormously from person to person, from multiple episodes per year to none at all.
Spreading Without Symptoms
One of the trickiest aspects of herpes is that the virus can be present on the skin with no visible sores. This is called asymptomatic shedding, and it’s a major reason herpes spreads so easily. A study published in JAMA found that people with symptomatic HSV-2 shed the virus on about 20% of days tested, while those who had never noticed symptoms still shed on roughly 10% of days. That means even people who don’t know they’re infected can transmit the virus.
Serious Complications
For most people, herpes is a manageable nuisance rather than a dangerous illness. But in certain situations, it can cause severe disease. Herpes simplex encephalitis, a brain infection caused by HSV, occurs in about 2 to 4 people per million each year. Without treatment, up to 70% of cases are fatal, and even with appropriate treatment, mortality runs 20% to 30%.
Transmission during childbirth is another serious concern. A mother experiencing her first genital herpes outbreak around the time of delivery has roughly a 57% chance of passing the virus to the newborn. For mothers with a recurrent outbreak, that risk drops to about 2%. Neonatal herpes can affect the skin, eyes, central nervous system, or internal organs, making it a medical emergency.
How Herpes Is Diagnosed
If you have active sores, a swab test can identify the virus directly. When no sores are present, blood tests that look for type-specific IgG antibodies are the standard approach. These tests identify whether your immune system has produced lasting antibodies against HSV-1 or HSV-2, with sensitivity ranging from about 88% to 98% and specificity from 83% to 100% depending on the specific test used.
IgM blood tests, which look for short-lived antibodies that suggest a recent infection, are far less reliable. They can take up to 10 days after exposure to become detectable, they cross-react with related viruses like the one that causes chickenpox, and they can turn positive during routine viral reactivation that has no clinical significance. For these reasons, type-specific IgG testing is preferred for identifying carriers.
Treatment and Management
There is no cure for herpes, but antiviral medications can reduce symptom severity, shorten outbreaks, and lower the risk of transmission. For a first genital herpes episode, antiviral treatment typically lasts 7 to 10 days and can be extended if sores haven’t fully healed. For recurrent outbreaks, shorter courses of 1 to 5 days can speed healing if started at the first sign of symptoms.
People who experience frequent recurrences have the option of daily suppressive therapy, taking a low dose of antiviral medication every day to keep the virus quiet. This approach reduces both the frequency of outbreaks and the rate of asymptomatic shedding. For pregnant women with genital herpes, suppressive therapy is typically recommended starting at 36 weeks of pregnancy to reduce the chance of an active outbreak at the time of delivery.
The practical reality for most people with herpes is that it behaves more like a recurring skin condition than a serious disease. Outbreaks tend to become less frequent over time, and many people eventually stop having them altogether. The virus is never eliminated from the body, but for the majority of carriers, it remains a latent infection rather than an active disease for most of their lives.