Cause:Streptococcus pyogenes(rarely Staph. aureus, which causes no sore throat)
Pathophys:Erythrogenic toxin produced by bacteria lysogenized by a specific phage, which causes bacterial capsular dilatation, rupture, and toxin release
Respiratory droplets and wound infections. Occurs in children only, since adults usually already immune
Sx:Sore throat, fever, rash
Si:Rash, trunkal, esp in creases (Pastia's lines), palpable, viral-like. Spots on soft palate. "Strawberry" tongue. Circumoral pallor
r/o other childhood exanthems: roseola, rubeola, rubella, erythema infectiosum (5th disease)
Lab:
Sore throat workup protocol (Ann IM 1980;93:244)
Bact:Throat culture, single swab positive in 75%, 2 swabs in 85% ß-hemolysis on culture plates. Positive culture may still be just a carrier. Rapid office tests but may still have to culture if negative (J Peds 1987;111:80)
Hem:Eosinophils increased often
Rx:Penicillin, erythromycin. If sick, treatment speeds healing (Jama 1975;227:1278)