Tongue in scarlet fever. Close-up of a rash on the tongue of a child with scarlet fever (scarlatina). Scarlet fever is a highly contagious disease, mainly of childhood, caused by Streptococcus sp. bacteria. It is transmitted by a patient or carrier (by coughing) or through contaminated milk. Symptoms occur 2-4 days after exposure and include fever, sickness, sore throat and a widespread scarlet rash affecting the torso, limbs and tongue. Treatment with antibiotics shortens the illness and prevents such complications as ear and kidney infections and swollen neck glands. An infection usually confers life-long immunity.