Herpes simplex - Viral skin infections

Viral skin infections

Herpes simplex

Definition

Herpes simplex virus (HSV) can cause a variety of clinical presentations.

Aetiology/pathophysiology

There are two subtypes:

HSV type 1 is usually the cause of perioral lesions, ocular infections, non-genital skin lesions and encephalitis. It spreads by direct contact with oral secretions and via droplet spread; infection is very common and most individuals are seropositive by adult life. Genital infections may occur due to orogenital contact. Immunocompromised patients are at particular risk for recurrent and disseminated infection.

HSV type 2 is transmitted by direct contact; it usually causes genital herpes and is therefore a sexually

transmitted disease.

After primary infection, the latent non-replicating virus resides within the dorsal root ganglion, shielding the virus from the immune system. Reactivation may follow exposure to sunlight, fever, trauma or emotional stress.

Clinical features

HSV type 1 primary infection usually occurs during childhood and is often asymptomatic. Symptomatic infection usually manifests as acute gingivostomatitis with vesicles on the lips and painful ulcers within the mouth accompanied by fever and malaise. Local herpes inoculation into a site of injury may present as a herpetic whitlow – a painful vesicle or pustule on a digit. Ocular infections and encephalitis  may occur with or without kin lesions.

HSV type 2 primary infection is often asymptomatic,

but may cause acute vulvovaginitis, penile or perianal lesions.

Latent infection occurs and recurrence is often heralded by a burning or tingling sensation. It usually occurs at the site of the primary infection and in adjacent areas. Hours or days later vesicles reappear.

Complications

Patients with atopic eczema may develop eczema herpeticum. Disseminated herpes may occur in the newborn or immunosuppressed. HSV is the most common cause of recurrent erythema multiforme.

Management

Aciclovir is of value if used early enough. Topical treatment at the onset of tingling may prevent a recurrence. As aciclovir works to prevent reactivation it is of limited value in established disease. However, immuno-suppressed patients should be treated aggressively with parenteral aciclovir to prevent dissemination.