Overview
Genital herpes describes a sexually transmitted infection (STI) due to herpes simplex, which has two strains, type 1 (HSV-1) and type 2 (HSV-2). They are associated with the development of small vesicles with an erythematous base on the skin or mucous membranes (cold sores).
HSV-1 is the most common cause or oro-labial herpes and is now the most common cause of genital herpes in the UK.
HSV-2 was previously thought to cause genital herpes, however, there is overlap between the two. This type is more likely to cause recurrent genital herpes.
Definitions
Primary infection – the first time HSV enters the body with no existing antibodies to either type. This is asymptomatic in most people with HSV-2.
Recurrent genital herpes describes the reactivation of HSV after a latent period.
Pathophysiology
Infection can occur via close contact with an infected individual as the virus can enter through mucosal surfaces or breaks in the skin. It can infect neurones and travel via the axon to the nerve ganglion, where it can lay dormant for years. Over time, it can reactivate and spread peripherally across sensory nerves, leading to symptoms.
Transmission
Viral shedding can occur from lesion sites, increasing the risk of transmission. In general:
- HSV-1 is usually spread through oro-genital sex
- HSV-2 is usually spread through vaginal/anal sex
However, genital herpes can be spread via contact with lesions at other sites.
Epidemiology
- In 2020, there were ~20,000 first episodes of genital herpes
- Peak incidence is in people aged 15-24 years old
Risk Factors
Risk factors for infection include:
- <25 years old
- Female sex
- History of other STIs
- Unprotected sexual intercourse
- Multiple sexual partners
- Men who have sex with men
- Immunocompromised states – such as HIV or immunosuppressant drugs
Risk factors for reactivation and recurrent infection include:
- Trauma (e.g. surgery, sexual trauma)
- Ultraviolet light (e.g. sunbathing, sun beds)
- Immunocompromised states – such as HIV or immunosuppressant drugs
Presentation
Overview
Primary infection tends to be worse than recurrent infections. Features include:
- A burning sensation followed by painful genital vesicles that form ulcers
- Associated features include fever, dysuria, pruritus, and tender inguinal lymphadenopathy
- Rectal proctitis may occur due to involvement of the rectum
Most cases (>50%) are symptomatic, therefore, the first presentation may represent reactivation.
- Recurrent attacks tend to be less severe and shorter in duration
- People may notice prodromal shooting pain/tingling/burning
- Recurrent genital lesions tend to localise in the same dermatome
Investigations
Overview
- Nucleic acid amplification test (NAAT) is the test of choice:
- May be performed on material from a popped fluid-filled blister
- A rectal swab may be taken if someone has features of herpes proctitis
Management
Overview
Management may involve the use of topical anaesthetics (e.g. lidocaine gel) and oral aciclovir within 5 days of the start of the episode while new lesions are forming. In some people with frequent relapses, long-term antivirals may be considered.
Pregnancy
If the person is pregnant at any gestation, they should be referred to a sexual health service and specialist to discuss care:
- First episode at >28 weeks – elective caesarean may be needed due to the high risk of vertical transmission
- Recurrent episodes – suppressive antiviral therapy is often used and the risk of vertical transmission is low
Complications
Progressive, multifocal, and coalescing lesions – more common in people who are immunocompromised (e.g. HIV or immunosuppressant drugs).
Autoinoculation (herpetic whitlow) – this may spread to adjacent skin or distant sites such as the arms and eyes.
Secondary infection – often due to Candida or Streptococcus species.
Urinary retention – this may occur due to pain or rarely, autonomic neuropathy.
Herpes proctitis – in people who engage in anal sexual intercourse.
Fulminant infection – this may cause aseptic meningitis, encephalitis, pneumonitis, hepatitis, and haemodynamic compromise, especially in people who are immunocompromised.
Prognosis
- Genital herpes is chronic and people tend to have 4-5 recurrences a year after HSV-2 infection
- HSV-2 recurrence rates are around 4 times higher than HSV-1
