Oral manifestations of viral infections in immunocompromised patients

Viral infections are a significant cause of morbidity and mortality in immunosuppressed patients. It is clear that diseases or medical treatments that have cytostatic or cytotoxic effects on lymphocytes and disrupt cytokine production or activity increase the risk of viral infections. While the rate of viral infection varies with the nature and degree of immunosuppression, it is clear that reactivation of latent virus is the most important determinant of the types of viral infections most frequently noted in immunosuppressed patients result from the reactivation of latent virus. Herpesviruses account for the majority of oral viral infections. Herpes simplex virus, varicella-zoster virus, and Epstein-Barr virus infections nearly always result from reactivation of latent virus, while cytomegalovirus infections, besides presenting as reactivated disease, are almost as likely to present as a primary infection in susceptible hosts. Other viral pathogens potentially of concern in immunocompromised patients are enteric viruses (adenoviruses and coxsackieviruses), human papillomaviruses, and possibly the recently identified human herpesvirus type 6. Ninety-eight percent of herpes simplex virus lesions are caused by reactivated disease and tend to be characterized by large, very painful ulcerative lesions throughout the mouth. Varicella-zoster virus is also rarely seen as primary infection, and the herpes zoster lesions involving cranial nerves can cause significant morbidity, including postherpetic neuralgia, corneal scarring, cranial nerve palsies, and deafness. Distinct oral ulcerative lesions caused by Epstein-Barr virus and cytomegalovirus have only recently been described in detail and are usually associated with disseminated disease. Oral human papillomavirus lesions are noted as warts and condylomas. The contribution of enteric viruses and human herpesvirus type 6 to oral disease in immunosuppressed patients is yet to be determined.