Herpes simplex virus infections

DESCRIPTION:   

Oral infection with herpes simplex virus occurs in three clinical forms. The most common type consists of recurrent small blisters on the lips commonly referred to as fever blisters or secondary herpes labialis. The second type is a generalized oral infection called primary herpetic stomatitis. The third and least common form of oral herpes infection consist of small ulcers usually localized on palatal mucosa.

Herpes labialis is illustration in Figs. 1 and 2. This lesion is well known and unlikely to be  a  diagnostic  problem.  It  tends  to  be  a  recurrent  disease  in  teenagers  and  adults. Elapsed time between recurrences varies from person to person. Recurrences are thought to be triggered by exposure to sunlight, febrile diseases, physical and psychogenic trauma, and other irritants.

Generalized involvement of the oral mucous membrane is called primary herpetic stomatitis and represents the initial exposure to the virus. This is a one time infection, but the patient remains susceptible to recurrent or secondary oral herpes infections (Figs. 3 and 4).

  It  is  more  commonly  seen  in  children,  but  teenagers  and  adults  are  also  affected.

Patients initially have gingivitis with swollen and red gingiva, then small blisters may appear on other mucosal surfaces. The blisters break quickly and are seldom seen by the dentist or physician. After they break, the lesions appear as small ulcers that resemble small aphthous lesions. The primary, generalized infection is accompanied by fever, cervical lymphadenitis, and inability to eat or drink without considerable pain. Patients who suffer recurrent intraoral herpes are few. Recurrent intraoral herpes infections  tend  to  occur  as  vesicles  followed  by  small  ulcers,  mainly  on  the  hard  palate mucosa (Fig. 5) and often follow trauma to the area, such as palatal injections or periodontal therapy.

ETIOLOGY:  

Herpesvirus hominis (herpes simplex virus). Most oral lesions are caused by Type I virus but approximately 10% are thought to be caused by Type II.

TREATMENT:   

Antiviral drugs such as Acyclovir, Famciclovir, Penciclovir, Valacyclovir and over-the-counter Abreva have all shown that they can decrease the time of disease as well as help with pain management. To be beneficial, they must be started at the first sign of disease. Most studies indicate that the drugs decrease the duration of disease by about one day. Acyclovir, Penciclovir and Abreva are available in a topical ointment.

PROGNOSIS:     

Primary  infection  usually  resolves  in  10-14  days.  Once  the  virus  has entered the body, it travels through nerve trunks to the nearest ganglion where it may lie dormant  for  the  remainder  of  the  patient's  life.  Future  recurrences  are  thought  to  be brought about by the "reawakening" of the virus which retraces its steps to cause new lesions in the same general area as the original point of entry. Thus, each recurrence is not a new and different infection from the outside but a recrudescence of the original infection. The ability of the virus to remain latent in deep ganglia makes total eradication almost impossible and will likely frustrate attempts at prevention for the foreseeable future.

Patients with widespread herpetic stomatitis should drink liquids to prevent dehydration. A broad-spectrum antibiotic is commonly given to control secondary bacterial infection, but does not shorten the viral infection. Antiviral drugs may shorten the duration of the disease if they are started early.

Clinicians should be aware that the herpesvirus may cause disseminated infection including encephalitis in which case the prognosis is extremely grave.

DIFFERENTIAL DIAGNOSIS:   

Primary herpetic stomatitis may resemble oral lesions of erythema multiforme, but herpes can be diagnosed by exfoliative cytology.A characteristic multinucleated cell appears in the smear of herpes infections. Culture of the virus is possible if a viral laboratory is available. Lesions of herpangina and hand, foot and mouth disease, both caused by Coxsackievirus, may clinically resemble oral herpes virus infections. Recurrent intraoral herpes may be confused with herpes zoster. Aphthous can be differentiated since it usually does not occur over bone, does not form vesicles and is not accompanied by fever or gingivitis.