Scarlet fever is a bacterial infection caused by group A Streptococcus. This illness affects people who have strep throat or streptococcal skin infections. Scarlet fever is treatable with antibiotics and also helps clear up symptoms faster and reduces spread to other people. Although anyone can get scarlet fever, it usually affects children between 5 and 12 years of age. The classic symptom of the disease is not the fever, but a certain type of red rash that feels rough, like sandpaper.