It is an infectious disease caused by streptococcus pyogenes ( group A strept.) , usually spread by inhalation ,it is most common in children 5-15 years of age . Scarlet fever features a bright red rash that covers most of the body this rash is caused by an erythrogenic toxin released from the bacterium (streptococcus pyogenes) ,it is almost accompanied by sore throat and high fever . The signs and symptoms include :
Red rash : The rash looks like a sunburn and feels like a sand paper ,it appears 12-72 hours after the fever start ,on the face it shows as red cheeks with characteristic pale area around the mouth (circumoral pallor) , it typically begins on the face or neck and spreads to the trunk ,arms and legs ,if pressure is applied to the rash it turns pale ,begins to fade 3-4 days after onset and desquamation begins .the rash may be itchy .
Red lines : The folds of skin around the groin ,axillae ,elbows ,knees and neck usually became a deeper red than the surrounding rash .
Flushed face : the face may appear flushed with a pale ring around the mouth . Strawberry tongue : the tongue look red and is often covered with a white coating early in the disease . Incubation period : 2-4 days .
Rarely scarlet fever can lead to rheumatic fever .
Differnitial diagnosis : kawasaki disease is an important differential especially in its incomplete form ,scarlet fever appears similar to kawasaki disease in some aspects but lacks the eye signs or the swollen red fingers and toes .
Penicillin or amoxicillin is the antibiotic of choice to treat scarlet fever. There has never been a report of a clinical isolate of group A strep that is resistant to penicillin. For patients with a penicillin allergy, recommended regimens include narrow-spectrum cephalosporins (e.g., cephalexin, cefadroxil), clindamycin, azithromycin, and clarithromycin.
Table: Antibiotic Regimens Recommended for Group A Streptococcal Pharyngitis
Drug, Route Dose or Dosage Duration or Quantity
For individuals without penicillin allergy
Penicillin V, oral Children: 250 mg twice daily or 3 times daily; adolescents and adults: 250 mg 4 times daily or 500 mg twice daily 10 days
Amoxicillin, oral 50 mg/kg once daily (max = 1000 mg); alternate:
25 mg/kg (max = 500 mg) twice daily 10 days
Benzathine penicillin G, intramuscular <27 kg: 600 000 U; ≥27 kg: 1 200 000 U 1 dose
For individuals with penicillin allergy
Cephalexin, oral 20 mg/kg/dose twice daily (max = 500 mg/dose) 10 days
Cefadroxil, oral 30 mg/kg once daily (max = 1 g) 10 days
Clindamycin, oral 7 mg/kg/dose 3 times daily (max = 300 mg/dose) 10 days
Azithromycin, oral 12 mg/kg once daily (max = 500 mg) 5 days
Clarithromycin, oral 7.5 mg/kg/dose twice daily (max = 250 mg/dose) 10 days