Herpes simplex

Created 2009.

Learning objectives

Identify and manage herpes simplex infections

Clinical features

Herpes simplex virus (HSV) type 1 mainly affects the face and type 2 mainly affects genital skin, although in 10% of infections the reverse is true and any mucocutaneous site may be affected.

The virus is inoculated into the affected area and is more likely with minor injury, e.g. facial lesions contracted in rugby (‘scrum pox’).

Primary type 1 HSV infections occur mainly in infants and young children, and are usually mild or subclinical but may result in severe ulceration, oedema, regional lymphadenopathy and systemic symptoms.
Type 2 infections occur mainly after puberty, often transmitted sexually.

Both type 1 and type 2 herpes simplex viruses reside in a latent state in spinal anterior horn cells. Recurrences are due to proliferation of virus within the epidermis of the affected dermatome and present as clusters of 2-3mm umbilicated clear or haemorrhagic vesicles. These persist for 5 to 10 days and are typically preceded by localised tingling or burning. Mild fever and malaise may occur. Asymptomatic viral shedding is also common.

Following the initial infection immunity develops but does not fully protect against further attacks in the same or new sites. However where immunity is deficient, both initial and recurrent infections tend to recur more frequently and to be more severe.

Complications may include:

Postinflammatory hypo- or hyperpigmentation or scarring
Localised neuralgia and/or paresis
Keratoconjunctivitis
Eczema herpeticum (severe primary herpes in patient with atopic dermatitis
Throat infections
Meningoencephalitis
Disseminated infection
Neonatal herpes infection

Recurrent herpes infections can be triggered by:

Localised trauma: dental procedure, injection, cosmetic treatment
Upper respiratory tract infections
Exposure to ultraviolet radiation
Premenstrual tension
Emotional stress and unknown factors

Herpetic gingivostomatitis

Recurrent herpes labialis

Recurrent facial herpes

Eczema herpeticum

Genital herpes

Primary herpes simplex

Investigations

The diagnosis may be confirmed by one of the following methods:

Viral culture of swab from vesicle (reported in about 5 days)
Immunofluorescence of basal cells collected from fresh vesicles onto slides for rapid identification (24 hours).
5ml plain tube blood or 500 µl serum for serology

Management

Topical therapy for mild herpetic infections may include:

Aciclovir cream
Penciclovir cream
Idoxuridine solution
Povidone iodine solution

Oral aciclovir is used for:

Severe primary or recurrent infections, 200mg five times daily commenced within 48 hours
Short-term prophylaxis, 400mg bd to cover facial surgery, cosmetic procedures or parturition
Long term prophylaxis (3 months to life long) for those with frequent significant recurrences

Resistant cases, 23 April 2005in the presence of HIV infection, may be treated with foscarnet

There are no other systemic antiherpetic drugs available in New Zealand. However, twice daily dosing is more convenient and possible with famciclovir and valciclovir.