|Sore throats may be associated with many medical conditions. Infections of the throat may be either viral or bacterial and are usually very contagious. Approximately 90 to 95% of all sore throats are caused by viruses such as the flu virus, a cold, or infectious mononucleosis (glandular fever).
Other sore throat causes, about 5-10%, are contributed to bacteria such as streptococcus, mycoplasma, or hemophilus. Bacterial sore throats are usually more serious than viral throat infections.
A common cause of bacterial throat infection is a particular strain of streptococcus bacteria of the group "A Streptococcus", and is commonly called strep throat. This specific bacterium can also cause damage to the kidneys and heart valves as well as causing tonsillitis, sinusitis, ear infections, pneumonia, or scarlet fever.