Strep throat is a bacterial infection affecting the upper respiratory tract, in which streptococcus bacteria cause throat pain, a raspy voice, and a scratchy, dry sensation in the throat. The throat pain is more severe than is typically experienced with the common cold or flu. Swollen lymph nodes and fever are common secondary symptoms. It is infectious and transmissible, but typically responds well to antibiotic drugs. In many cases, strep throat will begin to clear up within three to five days, even without treatment. However, in some cases, untreated strep throat can lead to serious complications, including systemic bacterial infections which may become life-threatening.