Herpes simplex orofacial infection

, Associate Editor-In-Chief:

Overview
Infection by HSV-1 is the most common cause of herpes that affects the face and mouth (orofacial herpes) although recent years are seeing an increase in oral HSV-2 infections. A majority of primary HSV-1 infections occur during childhood and, if the virus has come into contact with the mucosa or abraded skin, can cause acute herpetic gingivostomatitis (inflammation of the mucosa of the cheek and gums) within 5–10 days. Some other symptoms may also develop, including fever and sore throat, and painful ulcers may appear. Primary HSV infection in adolescents frequently manifests as severe pharyngitis with lesions developing on the cheek and gums. Some individuals develop difficulty in swallowing (dysphagia) and swollen lymph nodes (lymphadenopathy). Primary HSV infections in adults often presents as pharyngitis similar to that observed in glandular fever (infectious mononucleosis), but gingivostomatitis is less likely. The symptoms of primary HSV infection generally resolve within two weeks.

Once a primary oral HSV-1 infection has resolved, the HSV enters the nerves surrounding the primary lesion, migrates to the cell body of the neuron, and becomes latent in the trigeminal ganglion. In some people, the virus reactivates to cause recurrent infection - this is more common with HSV-1 than HSV-2 oral infection. Prodromal symptoms often precede a recurrence, which typically begins with reddening of the skin around the infected site, with eventual ulceration to form fluid-filled blisters that affect the lip (labial) tissue and the area between the lip and skin (vermilion border). The recurrent infection is thus often called herpes simplex labialis. Rare occasions of reinfections occur inside the mouth (intraoral HSV stomatitis) affecting the gums, alveolar ridge, hard palate, and the back of the tongue - this may be accompanied with herpes labialis.

Oral herpes is spread by direct contact with an active sore in an infected person, for instance, during kissing. However virus can be transmitted through the skin in the absence of a lesion. Oral herpes and cold sores can sometimes be confused with canker sores.