Herpes (HSV-1 and HSV-2)

Scale

WHO estimates around 3.8 billion people under 50 — roughly 64 percent of that population — have HSV-1, and around 520 million aged 15–49 have HSV-2. The large majority do not know.

Two viruses, historically split by site: HSV-1 as oral, HSV-2 as genital. That split no longer holds. HSV-1 is now the leading cause of new genital herpes in many high-income countries, transmitted by oral sex, particularly among people who reached adulthood without acquiring oral HSV-1 in childhood.

Symptoms, or the absence of them

Most people have no recognised symptoms. Others have mild symptoms attributed to something else — a cut, thrush, irritation, an ingrown hair.

A first episode, where symptomatic, can be significant: clusters of painful blisters or ulcers, fever, aching, swollen lymph nodes, and pain on urinating, lasting up to 2–3 weeks. Recurrences are shorter, milder and usually preceded by a prodrome of tingling, itching or nerve pain. Frequency declines over time in most people, and HSV-2 recurs more often than genital HSV-1.

Transmission

Skin-to-skin contact with the affected area, including when no lesion is present. Asymptomatic shedding accounts for most transmission — this is the central fact, and it is why "I've never had an outbreak" is not protection.

What reduces transmission, with figures:

• Daily suppressive antivirals. Corey et al. (2004, NEJM), in a randomised trial of 1,484 serodiscordant couples, found daily valaciclovir reduced clinically symptomatic transmission by 75 percent and overall HSV-2 acquisition by 48 percent.
• Condoms. Reduce transmission by roughly 30 percent (Martin et al., 2009, meta-analysis) — real, and limited by uncovered skin.
• Avoiding contact during prodrome and outbreak.
• Combined, these substantially lower risk. None eliminates it.

Testing: why it is not routine

Swabbing a lesion is accurate. Blood tests detect antibodies and cannot say where on the body the infection is, have a meaningful false-positive rate for HSV-2 at low index values, and do not change management in someone without symptoms. CDC, BASHH and the USPSTF all recommend against routine HSV serology in asymptomatic people. This means most sexual health screens do not include herpes, and many people assume a clear screen excludes it. It does not.

Serology is reasonable in specific situations: symptoms without a lesion to swab, a partner with known genital herpes, or pregnancy planning in a serodiscordant couple.

Treatment

Aciclovir, valaciclovir and famciclovir shorten and reduce outbreaks. Two approaches:

• Episodic: start at the first prodromal sign; shortens the episode by 1–2 days.
• Suppressive: daily dosing; reduces recurrence frequency by 70–80 percent, reduces asymptomatic shedding, and reduces transmission to a partner. Appropriate for frequent recurrences or for protecting a partner. Long-term safety data are good, extending over decades of use.

There is no cure. Therapeutic vaccine candidates remain in trials.

Pregnancy

Neonatal herpes is rare and serious. Risk is highest when a first infection is acquired in the third trimester, because the parent has not developed protective antibodies to pass on. Risk is low with recurrent herpes acquired before pregnancy. Management: suppressive antivirals from 36 weeks, and caesarean delivery if there are active lesions at labour. Tell the maternity team; this is straightforwardly manageable with information and dangerous without it.

Perspective

The stigma is disproportionate to the illness. Herpes is a common, manageable skin condition caused by a virus most of the human population carries. It does not affect fertility, does not cause cancer, does not shorten life, and for most people becomes a minor intermittent nuisance. Studies of the psychological impact consistently find distress driven by stigma and disclosure anxiety rather than by symptoms.

Disclosure to partners before sexual contact is the ethical standard and, in some jurisdictions, a legal one. A workable script: state it plainly, give the facts (suppression, condoms, avoiding outbreaks, actual risk figures), and let them decide. Many people react far better than expected once they learn how common it is.

Sources

• Corey L et al. "Once-daily valacyclovir to reduce the risk of transmission of genital herpes." NEJM, 2004.
• Martin ET et al. "A pooled analysis of the effect of condoms in preventing HSV-2 acquisition." Archives of Internal Medicine, 2009.
• James C et al. "Herpes simplex virus: global infection prevalence and incidence estimates." Bulletin of the WHO, 2020.
• USPSTF. "Serologic screening for genital herpes infection: recommendation statement." JAMA, 2023.
• BASHH. UK national guideline for the management of anogenital herpes, current edition.
• RCOG/BASHH. Management of genital herpes in pregnancy, current edition.

Last reviewed: August 2026.