Scarlet fever is a bacterial illness that develops in some people who have strep throat. Also known as scarlatina, scarlet fever features a bright red rash that covers most of the body. Scarlet fever is almost always accompanied by a sore throat and a high fever.
Scarlet fever is most common in children 5 to 15 years of age. Although scarlet fever was once considered a serious childhood illness, antibiotic treatments have made it less threatening. Still, if left untreated, scarlet fever can result in more-serious conditions that affect the heart, kidneys and other parts of the body.