Herpes simplex virus causes a self-limited primary infection that can be reactivated when there is a compromise in host resistance. Most orofacial herpetic infections are caused by herpes simplex virus type 1 (HSV-1), with the remainder being caused by HSV-2 (genital herpes). With changing sexual practices, oral HSV-2 is becoming increasingly common. Primary infections typically occur in children between 2 and 4 years of age and are often asymptomatic. However, in 10% to 20% of cases the primary infection manifests as acute herpetic gingivostomatitis, with abrupt onset of vesicles and ulcerations throughout the oral cavity. Most adults harbor latent HSV-1, and the virus can be reactivated, resulting in a so-called “cold sore” or recurrent herpetic stomatitis. Factors associated with HSV reactivation include trauma, allergies, exposure to ultraviolet light and extremes of temperature, upper-respiratory tract infections, pregnancy, menstruation, and immunosuppression. Recurrent lesions, which occur at the site of primary inoculation or in adjacent mucosa innervated by the same ganglion, typically appear as groups of small (1to 3-mm) vesicles. The lips (herpes labialis), nasal orifices, buccal mucosa, gingiva, and hard palate are the most common locations. Although lesions typically resolve within 7 to 10 days, they can persist in immunocompromised patients, who may require systemic anti-viral therapy. Morphologically, the lesions resemble those seen in esophageal herpes (see
Fig. 15.8 later in the chapter) and genital herpes (Chapter 19). The infected cells become ballooned and have large eosinophilic intranuclear inclusions. Adjacent cells commonly fuse to form large multinucleated polykaryons.
Fig. 15.1 Aphthousulcer.Singleulcerationwithanerythematoushalosur-roundingayellowishfibrinopurulentmembrane.
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Candidiasis is the most common fungal infection of the oral cavity. Candida albicans is a normal component of the oral flora and only produces disease under unusual circumstances. Predisposing factors include the following:
The specific strain of C. albicans
The composition of the oral microbial flora (microbiota)
Broad-spectrum antibiotics that alter the normal microbiota can promote oral candidiasis. The three major clinical forms of oral candidiasis are pseudomembranous, erythematous, and hyperplastic. The pseudomembranous form is most common and is known as thrush. This condition is characterized by a superficial, curdlike, gray to white inflammatory membrane composed of matted organisms enmeshed in a fibrinosuppurative exudate that can be readily scraped off to reveal an underlying erythematous base. In mildly immunosuppressed or debilitated individuals, such as diabetics, the infection usually remains superficial, but it may spread to deep sites in association with more severe immunosuppression, that may be seen in organ or hematopoietic stem cell transplant recipients, and in patients with neutropenia, chemotherapy-induced immunosuppression, or AIDS.
Aphthousulcersarepainfulsuperficialulcersofunknownetiologythatmayinsomecasesbeassociatedwithsystemicdiseases.
Herpessimplexviruscausesaself-limitedinfectionthatpresentswithvesicles(coldsores,feverblisters)thatruptureandheal,withoutscarring,andoftenleavelatentvirusinnerveganglia.Reactivationcanoccur.
Oralcandidiasismayoccurwhentheoralmicrobiotaisaltered(e.g.,afterantibioticuse).Invasivediseasemayoccurinimmunosuppressedindividuals.