Pharyngitis refers to infection and inflammation (becoming hot, swollen and red) of the structures in the pharynx. In most cases, the tonsils are affected and become inflamed and ulcerated (tonsillitis). In this section, we will describe the clinical manifestations, complications and treatment of pharyngitis. A better understanding of these points will help you to identify a child with pharyngitis and know that you should refer them to a higher level health facility. Pharyngitis can be caused by viruses or bacteria, but the most important causes are bacteria of the type known as Group A Streptococci. Infection with Group A Streptococci can lead to severe complications, including heart disease.