Herpes Simplex Infections

Herpes simplex virus

A range of infections, mainly viral, can produce oral blistering, but most patients present with ulceration after the blisters break. Herpesviruses are frequently responsible (Figure 9.1). Affected patients are largely children and there is often fever, malaise and cervical lymphadenopathy.

More severe manifestations and recalcitrant lesions are seen in immunocompromised people.

Herpes simplex

Definition: Herpes simplex virus (HSV) infection is common and affects mainly the mouth (HSV-1 or human herpesvirus-1; HHV-1), or genitals or anus (HSV-2; HHV-2). Initial oral infection presents as primary herpetic stomatitis (gingivostomatitis). All herpesvirus infections are characterized by latency (Figure 9.2), and can be reactivated. Recurrent disease usually presents as herpes labialis (cold sore).

Prevalence (approximate): Common. Age mainly affected: Herpetic stomatitis is typically a childhood infection seen between the ages of 2–4 years, but cases are increasingly seen in the mouth and/or pharynx in older patients.

Gender mainly affected: M : F.

Etiopathogenesis: HSV, a DNA virus, is contracted from infected skin, saliva or other body fluids. Most childhood infections are with HSV-1, but HSV-2 is often implicated more often at later ages, often transmitted sexually. UNC-93B1 gene mutations predispose to herpesvirus infection.

Diagnostic features

History: The incubation period is 4–7 days. Some 50% of HSV infections are subclinical and may be thought to be “teething” because of oral soreness.

Clinical features: Primary stomatitis presents with a single episode of multiple oral vesicles which may be widespread, and break down to form ulcers that are initially pinpoint but later fuse to produce irregular painful ulcers (Figure 9.3). Gingival edema, erythema and ulceration are prominent (Figure 9.4). The tongue is often coated and there may be oral malodor.

Herpetic stomatitis probably explains many instances of “teething”.

Extraoral features: Commonly include malaise, drooling, fever and cervical lymph node enlargement.

Complications of HSV infection occasionally include erythema multiforme or Bell palsy. HSV-1 appears to increase the risk of developing Alzheimer disease. Rare complications include meningitis, encephalitis and mononeuropathies, particularly in people with impaired immunity, such as infants whose immune responses are still developing, or immunocompromised patients.

Differential diagnosis:Other oral infections and leukemic gingival infiltrates.

Investigations: The diagnosis is largely clinical but blood tests to exclude leukemia (full blood picture and white cell count) may be indicated, and a rising titer of serum antibodies is diagnostically confirmatory but only retrospectively. Cytology, viral DNA sequentiation, culture, immunodetection or electron microscopy are used occasionally (Figures 9.5a–c).

Management

Treatment aims to limit the severity and duration of pain, shorten the duration of the episode, and reduce complications. Management includes a soft diet and adequate fluid intake. Antipyretics/analgesics such as paracetamol help relieve pain and fever. Products containing aspirin must not be given to children with any fever-causing illness suspected of being of viral origin, as this risks causing the serious and potentially fatal Reye syndrome (fatty liver plus encephalopathy).

Local antiseptics (0.2% aqueous chlorhexidine mouthwashes) may aid resolution. Aciclovir orally or parenterally is useful especially in immunocompromised patients. Valaciclovir or famciclovir may be needed for aciclovir-resistant infections.

Prognosis

Good, though HSV remains latent thereafter in the trigeminal ganglion and recurrences may occur.

Recurrent herpes labialis

Definition: Recurrent blistering of the lips caused by HSV reactivation. Prevalence (approximate): 5% of adults.

Age mainly affected: Adults.

Gender mainly affected: M = F.

Etiopathogenesis: HSV latent in the trigeminal ganglion travels to mucocutaneous junctions supplied by the trigeminal nerve, producing lesions on the upper or lower lip, occasionally the nares or the conjunctiva or, occasionally intraoral ulceration. Fever, sunlight, trauma, hormonal changes or immunosuppression can reactivate the virus which is shed into saliva, and there may be clinical recrudescence.

Diagnostic features

History: Oral premonitory symptoms may be tingling or itching sensation on the lip in the day or two days before, followed by appearance of macules, then papules, vesicles and pustules.

Clinical features: Oral lesions start at the mucocutaneous junction and heal usually without scarring in 7–10 days (Figure 9.6). Widespread recalcitrant lesions may appear in immunocompromised patients.

Extraoral: Occasionally lesions become superinfected with Staphylococcus or Streptococcus, resulting in impetigo. In immunocompromised persons, extensive and persistent lesions may involve the perioral skin. In atopic persons, the lesions of herpes labialis may spread widely to produce eczema herpeticum.

Differential diagnosis:Impetigo and other causes of blisters.

Investigations are rarely needed as the diagnosis is largely clinical.

Management

Penciclovir 1% cream, aciclovir 5% cream or silica gel applied in the prodrome may help abort or control lesions in healthy patients. Systemic aciclovir or other antivirals may be needed for immunocompromised patients.

Prognosis

Usually good but immunocompromised patients can develop recalcitrant lesions.

Recurrent intraoral herpes

Recurrent intraoral herpes in healthy patients tends to affect the hard palate or gingiva, as a small crop of ulcers usually over the greater palatine foramen, following local trauma (e.g. palatal local anesthetic injection), and heals within 1–2 weeks.

Recurrent intraoral herpes in immunocompromised patients may appear as chronic, often dendritic, ulcers frequently on the tongue ( herpetic geometric glossitis). Clinical diagnosis tends to underestimate the frequency of these lesions.

Management: The aims are to limit the severity and duration of pain, shorten the duration of the episode, and reduce complications. Symptomatic treatment with a soft diet and adequate fluid intake, antipyretics/analgesics (paracetamol), local antiseptics (0.2% aqueous chlorhexidine mouthwashes) usually suffices. Systemic aciclovir or other antivirals may be needed for immunocompromised patients.