Genital herpes

Organism

Genital herpes can be caused by either Herpes simplex virus type 1 (HSV-1) which is the usual cause of oro-labial herpes, or by H. simplex virus type 2 (HSV-2). HSV infection may be acquired from either symptomatic or asymptomatic partners, and from either genital or oral sexual contact. The majority of recurrent genital infections are caused by HSV-2.

The incubation period ranges from 2-12 days but can be for years. The period of infectivity is 2-7 weeks after primary infection, and 5 days after recurrences. Intermittent shedding may be lifelong in presence or absence of clinical lesions. Contact infectivity is high if lesions are present, lower if no lesions.

Clinical presentation

Most HSV infections are asymptomatic. Clinical manifestations depend on the site of viral entry, and immunity from previous oral or genital HSV exposure. Manifestations of newly acquired infection may be severe in non-immune persons who have had no previous exposure. Primary infection is a systemic disease, and flu-like illness can occur. Initial infections are less severe in persons with prior exposure to HSV-1. Sexually acquired manifestations include genital ulceration, urethritis, cervicitis, proctitis and gingivostomatitis.

First noticed lesions can be multiple, widespread, bilateral, at different stages of development and resolution, and at sites of direct mucosal infection. Recurrent lesions are typically grouped and localised, unilateral, at identical stages of development and at cutaneous sites along sacral dermatomes. Autoinoculation can occur with primary infection and patients should be counselled to prevent this occurring.

STI Atlas (external site)

Investigations

Swab for NAAT

Special considerations

A negative test result does not exclude HSV infection. The tests above are the preferred tests because they are cost efficient and identify the anatomical site of infection. Currently, a positive test is required to meet PBS requirements for suppressive therapy.

Type specific herpes serology is available and may be useful in the following circumstances:
- to aid diagnosis in lesions which are consistently virus negative
- to assist in counselling in couples where one is known to be positive and the other is unknown.

Serology is not a substitute for NAAT or culture.

Treatment

First episode

Valaciclovir 500 mg orally, 12-hourly for 5 to 10 days

aciclovir 400 mg orally, 3 times daily for 5 to 10 days.

Recurrent herpes

Episodic

Episodic treatment is indicated for infrequent recurrences (i.e. intervals of more than six to eight weeks). Episodic therapy should be initiated early on by the patient at the first sign of prodrome or very early lesions.

Valaciclovir 500 mg orally, 12-hourly for 3 days

famciclovir 1g orally stat

aciclovir 800 mg orally, 3 times daily for 2 days.

Suppressive therapy

Suppressive therapy is indicated in significant, frequent disease.

Valaciclovir 500 mg orally, daily

famciclovir 250 mg orally, 12-hourly

aciclovir 200 mg orally, 8-hourly.

For immunocompetent individuals having at least 10 out-breaks per year, or immunosuppressed individuals:

valaciclovir 1 g orally, per day

famciclovir 500 mg orally, 12-hourly

aciclovir 400 mg orally, 12-hourly.

There is no evidence that vitamins, zinc, lysine or other complementary remedies are any more effective than placebo in the prevention of recurrences.

Pregnancy

Aciclovir (category B3) is not recommended for routine use during pregnancy. However, it may be used in individual cases when the patient's condition requires it.

Perinatal transmission, with disseminated HSV infection in the neonate, is most likely to occur with vaginal delivery at the time of, or shortly after, primary maternal infection. The risk is much lower with recurrent HSV lesions or asymptomatic infection at the time of delivery in a woman with a history of genital herpes because passive cross-placental transfer of maternal antibodies provides good protection for the baby. A woman with a history of genital herpes, or who has had a partner with herpes, should alert her obstetrical team to this situation. The decision whether to proceed to vaginal delivery depends on the presence of lesions at term, availability and results of virological tests, and the outcome of discussion between the obstetrician and the mother.

Australian categorisation system for prescribing medicines in pregnancy (external site)