scarlet fever: group A streptococcal bacteria ( S. pyogenes )-fever, lethargy, sore throat, and a bumpy rash that blanches under pressure. The sandpaper rash appears first on the upper chest and spreads to the neck, abdomen, legs, arms, and in folds of skin such as under the arm or groin. In scarlet fever, the skin around the mouth tends to be pale, while the cheeks are flushed. The patient usually has a "strawberry tongue," dark red lines (called Pastia's lines) may appear in the creases of skin folds. After the fever is gone, the skin on the face and body flakes; the skin on the palms of the hands and soles of the feet peels more dramatically Rx: penicillin