Look at this patient's mouth.

Salient Features
Pain, itching, burning lasting several hours.· Vesicles.· Sore mouth.· Fever.· Gum swelling.· Mouth ulcers.

Small vesicles with an erythematous base on the lips and around the mouth.

Proceed as follows:
Look for vesicles in the mouth (gingiva, tongue, soft and hard palate) and pharynx.Tender anterior cervical lymph nodes.

This patient has small vesicles around the mouth (lesion) due to herpes labialis(aetiology), which is causing severe itching (functional status).

What usually causes a 'cold sore'?
Herpes simplex virus (HSV) type I: in children it causes asymptomaticgingivosto-matitis; in adults there may be severe stomatitis with mouth ulcers, locallymph node enlargement and systemic features.

What do you know about HSV-II?
HSV-II causes genital infection, called vulvovaginitis. Women with genital herpes oughtto have cervical screening as a link with carcinoma of the cervix is suspected. There hasrecently been a dramatic increase in the prevalence of HSV-II infection (N Engl J Med1997; 337:1105-11).

What are the complications of herpes infection?·
Erythema multiforme.· Disseminated infection in the immunocompromised individual.· Herpes keratitis, scarring and visual impairment.· Herpes simplex encephalitis (propensity for the temporal lobe).· Herpetic whitlow (infection of the finger; Fig. 12).· Herpes gladiatorum (infection of the skin, described among wrestlers).· Visceral infections, especially in viraemia in HIV (oesophagitis, pneumonitis,hepatitis).· Neonatal HSV infection (neonates less than 6 weeks of age); usually visceraland/or central nervous system infection.· Herpes simplex meningitis.

How would you confirm your clinical diagnosis?
Scrapings of the base of the lesions stained with either Wright, Giemsa (Tzanckpreparation) or Papanicolaou's stain will demonstrate characteristic giant cells orintranuclear inclusions of herpes infection (does not differentiate from zoster infection).· Isolation of virus in tissue culture.· Demonstration of HSV antigens in scrapings from lesions.

How would you treat herpes labialis?
Aciclovir cream applied locally.

What drugs are available for herpes simplex infections?
Mucocutaneous herpes: topical aciclovir, foscarnet.· Eye infections: idoxuridine, trifluorothymidine, topical vidarabine. Prophylacticuse of aciclovir can prevent recurrent ocular HSV disease (N Engl J Med 1998; 339:300-6).· Encephalitis: intravenous aciclovir.· Neonatal infections: high-dose intravenous vidarabine and aciclovir.In a patient suspected of herpes encephalitis,

which test allows early detection?

HSV DNA polymerase chain reaction (PCR) in the cerebrospinal fluid.