Herpes Simplex

Synonyms

Cold sore; fever spot; herpes; (herpetic) whit low; HSV.

Epidemiology

About 90% of adult population have evidence of previous infection.

Definition

Viral infection with herpes simplex virus types 1 and 2.

Aetiology & Pathogenesis

Primary or secondary infection with the more common herpes simplex virus; Type 1 (H. labialis) or less frequently; Type 2 (H. genitalis). These DNA viruses are epidermotropic and neurotropic. Transmission: fomites (contaminated surfaces) or direct contact. Reservoir: humans. Incubation period: 2-7 days.

Signs & Symptoms

Painful, grouped vesicles (herpetiform) on an erythematous base which quickly evolve into pustules.

Primary infection:

Herpetic gingivostomatitis.
Herpes genitalis (including herpetic vulvovaginitis).
Herpes neonatorum.

Secondary infections:

Recurrent herpes simplex labialis (Type 1) or genitalis (Type 2), herpetic keratitis, eczema herpeticum.
Aetiology: endogenous re-infection, usually at the same site, triggered by UV light, stress, hormonal changes and other factors.

Localisation

Lips, mouth, fingers, ano-genital skin, buttocks or potentially any part of the skin or intermediate epithelium/mucous membranes.

Classification

Viral subtypes 1 and 2.

Laboratory & other workups

Usually not required. Antigen test or PCR to differentiate type 1 from type 2. Tzanck smeartest: Multinucleate keratinocytes (giant cells with viral inclusion bodies).

Dermatopathology

Not usually required. Balloon degeneration of keratinocytes in blister.

Course

Usually self-limiting. Individual periodicity of reactivation.

Complications

Persistent ulceration, eczema herpeticum, secondary bacterial infection, keratitis potentially leading to blindness, viral encephalitis, erythema multiforme.

Diagnosis

Clinical. Laboratory tests only in cases of diagnostic difficulty.

Differential diagnosis

Impetigo, sexually transmitted infections (STI) , aphthous ulcers.

Prevention & Therapy

Topical: astringents, antiseptics, virostatics.

Systemic: virostatics (e.g. aciclovir).
Indications:

Herpes vulvitis and stomatitis.
Herpes neonatorum.
Herpes labialis with erythema multiforme.
Herpes genitalis.
Treatment of recurrent disease either at first sign of disease or as long-term prophylactic therapy.

Special

Beware disseminated infection in those with atopic dermatitis (eczema herpeticum) or those who are immunocompromised. All ano-genital HSV needs investigation for other sexually transmitted diseases.

2.1.2 Herpes Simplex