Describe the appearance of the upper and lower gingivae in Figure 40.1.

There is erythematous gingival enlargement with small ulcerations of the gingival margin.

What is the diagnosis?

Primary herpetic gingivostomatitis.

There are two types of herpes simplex virus: herpes simplex type 1 (HSV-1) and herpes simplex type 2 (HSV-2). Classically HSV-1 causes oral disease and HSV-2 causes genital disease. The viruses, however, are very similar and both can cause both oral and genital disease, although there are differences in recurrence rates. Primary exposure to HSV in the mouth causes acute primary herpetic gingivostomatitis (Fig. 40.1). The virus causes a viraemia, fever, malaise and lymphadenopathy. All the surfaces of the mouth including the hard palate and attached gingiva can be involved, initially with a vesicular rash that ulcerates and becomes superinfected. The illness lasts for 10–14 days before resolving spontaneously. Diagnosis is usually made on clinical grounds but can be confirmed by a threefold rise in the convalescent antibody titre over that seen in the acute phase or by direct immunofluorescence of vesicular fluid using specific antisera.

The primary infection may be mild and subclinical in the majority of young children who are exposed to it, though the condition may be severe and debilitating, and in an immunocompromised individual may lead to severe illness and sometimes herpetic hepatitis or encephalitis, which may be fatal in the absence of treatment.

Oral infection arises from direct contact with secretions from an individual who either has a primary or recurrent HSV infection. Direct inoculation of the fingers or skin with virally contaminated secretions or fluid can lead to local infection, e.g. herpetic whitlow of finger.

HSV is a neurogenic virus, and on recovery from the primary infection the virus may become latent within the trigeminal ganglion or basal ganglia of the brain and may subsequently be reactivated to cause a secondary infection. The secondary infection may cause a ‘cold sore’ on the lip or Bell’s palsy.

What are the reasons given for the reactivation of HSV to produce a cold sore (herpes labialis) (Fig. 40.2)?

See Box 40.1.

Fig. 40.2 Recurrent herpes ‘cold sore’.