There are two types of herpes simplex virus (HSV) - HSV-1 and HSV-2. The types of infection with herpes simplex include:
- First episode primary infection - HSV confirmed in a patient without prior findings of HSV-1 or HSV-2 antibodies.
- First episode non-primary infection - HSV-2 confirmed in a patient with prior findings of HSV-1 antibodies or vice versa.
- First recognised recurrence - HSV-1 or HSV-2 confirmed in a patient with prior findings of HSV-1 or HSV-2 antibodies.
HSV-1 is the major cause of herpetic stomatitis, herpes labialis (cold sore), keratoconjunctivitis and encephalitis. However, HSV-1 can also sometimes cause genital herpes by genital contact with oral lesions.
Although approximately 70 per cent of people are infected with HSV-1, only about 30 per cent will have recurrent infections. The herpes virus initially causes a primary infection, which can be asymptomatic. Alternatively, some patients develop vesicles and very painful ulcers in and around their mouths.
The herpes virus then remains latent, usually in the trigeminal ganglia. This leads to the formation of herpes labialis, commonly known as a cold sore. This is often preceded by an area of numbness or tingling on the lip. The risk of transmission to other people is highest for 1-4 days from the onset of symptoms, although patients may remain infectious for up to 12 days.
Herpes can be reactivated by:
- Extremes of heat (cold and warmth);
- Febrile illness;
- Ultraviolet light (sunshine).
The benefits of topical antivirals (eg aciclovir cream) are small and the cold sores will usually resolve within 7-10 days without treatment. Oral antiviral drugs do not cure a patient or prevent future episodes of cold sores. Simple analgesics may be required to control the pain associated with the lesions. The use of topical antivirals as prophylaxis is ineffective.
Complications of HSV-1
Most cases are self-limiting and improve with (or without) treatment and without complications within 1-3 weeks.
However, complications can lead to dendritic ulcers, keratitis, herpetic whitlow, erythema multiforme, scarring from recurrent lesions and secondary bacterial infection. Rarely, meningitis or encephalitis can occur.
HSV-2 causes genital herpes, although this serotype can also cause pharyngitis and in immunocompromised patients, systemic infection. Genital herpes is one of the most common STIs worldwide and its incidence is increasing in the UK.
The primary infection in HSV-2 infections is usually more severe than in HSV-1. The herpes virus usually remains latent in the sacral ganglia. Recurrences can affect the mucous membranes of the genital tract, rectum, mouth and oropharynx.
The majority of genital herpes infections are acquired sub-clinically; at least 80 per cent of people with proven HSV are unaware that they have been infected. The primary infection can be associated with systemic symptoms, which include fever, myalgia and headache. Patients often complain of tingling neuropathic pain in the genital area and buttocks.
Multiple bilateral painful shallow ulcers or blisters often appear, which then join together. In women, the vagina and cervix are also affected. Dysuria and vaginal or urethral discharge can also occur.
These symptoms can be associated with tender inguinal lymphadenopathy. Without treatment, these symptoms can last for up to four weeks and recurrent infection usually leads to milder symptoms, which are more short-lived.1
The lesions then tend to be unilateral. Patients experience an average of five attacks in the first two years after acquiring the HSV virus. But the subsequent attacks usually become less frequent over time.
Although the diagnosis is usually a clinical one, a swab is required for a definitive diagnosis to be made. The herpes virus is most easily isolated from new lesions. HSV detection by polymerase chain reaction (PCR) increases detection rates by up to 71 per cent compared with viral culture, but is still not widely available in the UK.
Serology is sometimes offered in the following situations:2
- If the patient's partner has genital herpes and the patient wants to know if he or she has been infected.
- The patient presents with recurrent genital or atypical ulcers and results of culture or PCR tests are negative.
- Screening of patients at high risk of STIs.
- Testing of pregnant women with undiagnosed genital herpes.
Ideally, all patients with suspected genital herpes should be referred to a specialist in genito-urinary medicine for diagnosis, treatment, screening for STIs, counselling and follow up.
It is essential to refer pregnant women, immunocompromised patients, those with severe local secondary infection and anyone with systemic herpes infection (eg meningitis); this is uncommon.
Treatment for HSV-2
The British Association for Sexual Health and HIV have produced national guidelines for the management of genital herpes.
For the primary infection, general advice should be given - saline baths, simple analgesia, topical anaesthetic agents (eg 5% lidocaine ointment can be useful).
Antiviral drugs are indicated within five days of the start of the episode and while new lesions are forming. Combining oral and topical antivirals is of no benefit.
For recurrent infections, treatment depends on the type and severity of symptoms with which the patient presents. General advice should be recommended.
For patients with severe symptoms, antivirals can be given. Patients who have more than six episodes a year could be considered for long-term oral antiviral treatment for up to a year.
Asymptomatic viral shedding can be reduced by aciclovir.3 One study has shown that daily suppressive treatment with valaciclovir can reduce HSV-2 transmission in serodiscordant couples by 75 per cent.4
Although the symptoms of a recurrence of HSV-2 are usually considerably less when compared with a primary infection, the psychological impact should not be underestimated.
Patients and their partners need to be given detailed information about the nature of this condition. Patients should be informed that asymptomatic viral shedding is more common in genital HSV-2 infections.
Patients with a first episode of genital herpes should be told that this does not necessarily indicate recent infection and that genital symptoms may develop several years after the infection is acquired.
HSV in pregnancy
Infection can spread to the baby either via the placenta or during childbirth. Primary infections acquired in the first or second trimester can be treated with either oral or IV antiviral medication.
Caesarean section should be offered to women presenting with first-episode genital herpes lesions at or after 34 weeks' gestation. However, vaginal delivery is appropriate if no lesions are present at delivery. Caesarean section should be considered for women with recurrent genital herpes lesions at the onset of labour.
- Dr Newson is a GP in the West Midlands.
1. Gupta R, Warren T, Wald A. Genital herpes. Lancet 2007; 370: 2,127-37.
2. Sen P, Barton S E. Genital herpes and its management. BMJ 2007; 334: 1,048-52.
3. Wald A, Zeh J, Barnum G, Davis L G, Corey L. Suppression of subclinical shedding of herpes simplex virus type 2 with acyclovir. Ann Intern Med 1996; 124: 8-15.
4. Corey L, Wald A, Patel R, Sacks S L et al. Once-daily valacyclovir to reduce the risk of transmission of genital herpes. N Engl J Med 2004; 350: 11-20.
- BASHH (2007). 2007 national guideline for the management of genital herpes. Clinical Effectiveness Group, British Association for Sexual Health and HIV. www.bashh.org
- Herpes Viruses Association www.herpes.org.uk