Scarlet fever is an infectious disease which most commonly affects 4-8 year old children. Symptoms include sore throat, fever and a characteristic red rash. It is usually spread by inhalation. There is no vaccine, but the disease is effectively treated with antibiotics. Before the availability of antibiotics, scarlet fever was a major cause of death. It could also cause late complications such as glomerulonephritis and endocarditis leading to heart valve disease, all of which were protracted and often fatal afflictions at the time. Scarlet fever is caused by erythrogenic toxin, a substance produced by the bacterium Streptococcus pyogenes when infected by a certain bacteriophage. The term scarlatina may be used interchangeably with scarlet fever, though it is most often used to indicate the less acute form of scarlet fever seen since the beginning of the twentieth century. This disease is most common in 4-8 year olds with males and females being equally affected.