Many other infectious processes can invade the upper respiratory tract and adjacent regions of the head and neck. Common viral infections of the oropharynx are primary herpes simplex gingivostomatitis and adenovirus and coxsackievirus infections.
Spirochetes play a role in ulcerative gingivitis and periodontitis.
Actinomyces israelii can produce chronic burrowing infections of the gums and jaw, occasionally with secondary involvement of the respiratory tract. Fungal diseases, such as histoplasmosis and South American blastomycosis, and parasitic diseases, such as leishmaniasis, may involve the upper respiratory tract. Although rare in the United States, rhinoscleroma can occur in immigrants from developing countries or in HIV-infected persons. Many bacterial species have been implicated in a variety of dental infections. Dental infection is the leading cause of necrotizing cervical fasciitis.