Herpes Simplex Infections
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Direct answer
Herpes simplex infections are caused by herpes simplex virus types 1 and 2 and produce grouped vesicles on an erythematous base that soon ulcerate and crust. HSV-1 is the usual cause of orolabial disease, while the skin forms vary with the site and the host, from cold sores to eczema herpeticum. The high-yield forms are eczema herpeticum, which can be life-threatening, and herpetic whitlow, an occupational risk for health workers.
What you must remember
- Orolabial herpes: HSV-1 causes most cold sores, with a prodrome of tingling before grouped vesicles appear on the lip margin.
- Primary gingivostomatitis: HSV-1 infection in young children causes fever, painful oral vesicles and ulcers, and fluid intake needs watching.
- Eczema herpeticum: HSV superinfection of atopic dermatitis presents as umbilicated, punched-out vesicles and erosions with fever, and it is a dermatological emergency.
- Herpetic whitlow: HSV infection of the finger pad, typical of dentists, nurses and other health workers, with painful grouped vesicles and swelling.
- Herpes gladiatorum: skin-to-skin transmission in wrestlers and athletes, with lesions on the face, neck and trunk.
- Ocular involvement: dendritic keratitis is the main eye complication and needs urgent ophthalmology review.
- Treatment: oral aciclovir or valaciclovir for orolabial disease and whitlow, and systemic aciclovir for severe disease such as eczema herpeticum.
Forms of HSV infection by site
Herpes simplex infections are classified by the site where the virus establishes itself, and the clinical form predicts both the complications and the management. The table lists the forms that examiners most often test.
| Form | Typical setting | Key feature |
|---|---|---|
| Herpes labialis | Adults with recurrent cold sores | Grouped vesicles on the lip margin after a prodrome |
| Gingivostomatitis | Young children, first infection | Painful oral vesicles, ulcers and fever |
| Eczema herpeticum | Patients with atopic dermatitis | Umbilicated, punched-out vesicles, widespread and febrile |
| Herpetic whitlow | Dentists, nurses and other health workers | Painful vesicles and swelling on the finger pad |
| Herpes gladiatorum | Wrestlers and athletes | Lesions on the face, neck and trunk after contact |
The table tracks where the infection lands rather than the virus type, which is why the same HSV can cause very different disease. Eczema herpeticum and herpetic whitlow are the high-yield forms, because one is a systemic emergency and the other is an occupational hazard. Recognising the setting, the age of the patient and the presence of atopy usually points to the correct form before a test is sent.
Where the exam plants its traps
Stems on herpes simplex test the recognition of the forms, the safe management of the whitlow and the seriousness of eczema herpeticum.
- Trap: incising a herpetic whitlow to drain pus Correct: it is a viral lesion, incision can spread infection, and the diagnosis is made by swab or PCR and treated with aciclovir.
- Trap: treating eczema herpeticum with topical steroids alone Correct: the infection needs systemic aciclovir, and steroids are not used to treat the viral infection.
- Trap: dismissing a red eye with a herpes history as simple conjunctivitis Correct: herpetic keratitis threatens the cornea and needs urgent ophthalmology review with topical antiviral therapy.
Frequently asked questions
Why is eczema herpeticum considered a medical emergency?
Eczema herpeticum is a widespread HSV infection of atopic skin that can disseminate, become superinfected with bacteria and involve the eye. Fever and widespread erosions signal serious risk, so systemic aciclovir and hospital review are needed in severe cases.
What is herpetic whitlow and who is at risk?
Herpetic whitlow is HSV infection of the finger pad, causing painful grouped vesicles and swelling, and it occurs most often in dentists, nurses and other health workers. Incision and drainage should be avoided because it can spread the virus.
Which HSV type causes orolabial herpes and primary gingivostomatitis?
HSV-1 is the usual cause of orolabial herpes and primary gingivostomatitis, although HSV-2 can cause orolabial disease through oral-genital contact. Primary gingivostomatitis is most common in young children, who need their fluid intake monitored.
What is the test of choice for diagnosing herpes simplex lesions?
PCR on fluid taken from the base of an unroofed vesicle is the test of choice for herpes simplex lesions, and it identifies the viral type. The Tzanck smear is quicker but non-specific, because it cannot distinguish HSV from varicella-zoster virus.
What is the main eye complication of herpes simplex infection?
Herpes simplex keratitis, classically dendritic keratitis, is the main ocular complication of HSV infection, and it can threaten corneal sensation and vision. It needs urgent ophthalmology review and topical antiviral therapy.