Causes, Incidence and Risk Factors Pharyngitis is most often caused by a viral infection, or by a bacterium.
Viral pharyngitis is the most common cause of a sore throat .
When cultures of the throat fail to reveal bacterial causes for the symptoms, a viral pharyngitis is suspected. Risk factors include recent upper respiratory infection . The incidence is 3 out of 100 people. A throat swab culture does not show streptococcal or gonorrheal infection. There is no specific treatment for viral pharyngitis .