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Scarlet Fever
Scarlet fever (SF) is an acute infection of the tonsils, skin, or other sites by an erythrogenic exotoxin-producing strain of group A streptococcus (GAS), associated with a characteristic toxigenic exanthem.
Causes of Scarlet Fever
Erythrogenic toxin production depends on the presence of a temperate bacteriophage. Patients with prior exposure to the erythrogenic toxin have antitoxin immunity and neutralize the toxin. The SF syndrome therefore does not develop in these patients. Since several erythrogenic strains of GAS cause infection, it is theoretically possible to have a second episode of SF. Strain of S. aureus can synthesize an erythrogenic exotoxin, producing a scarlatiniform exanthem.
Symptoms of Scarlet Fever
The rash is the most striking sign of scarlet fever. It usually begins looking like a bad sunburn with tiny bumps and it may itch. The rash usually appears first on the neck and face, often leaving a clear unaffected area around the mouth. It spreads to the chest and back, then to the rest of the body.
Aside from the rash, there are usually other symptoms that help to confirm a diagnosis of scarlet fever, including a reddened sore throat, a fever above 101 degrees Fahrenheit (38.3 degrees Celsius), and swollen glands in the neck. The tonsils and back of the throat may be covered with a whitish coating, or appear red, swollen, and dotted with whitish or yellowish specks of pus.
Other less common symptoms include:
- Nausea and vomiting
- Headache
- Body aches
Diagnosis
Clinical findings confirmed by detecting streptococcal antigen in a rapid test and/or culturing GAS from throat or wound.
Treatment
Symptomatic therapy
Systemic antimicrobial therapy
Penicillin V
For penicillin-allergic patients:
Erythromycin estolate
Erythromycin ethylsuccinate
Azithromycin
Clarithromycin
Cephalosporin (for those who cannot
tolerate oral erythromycin)
Follow-Up
Aspirin or acetaminophen for fever and/or pain. Penicillin is the drug of choice because of its efficacy in prevention of rheumatic fever. Goal is to eradicate GAS throat carriage.
1.2 million units IM (adults); 600,000 units IM (children <60 Ibs).
250 mg PO qid for 10 days.
20 to 40 mg/kg/d.
40 mg/kg/d.
Reculture of throat recommended for individuals with history of rheumatic fever or if a family member has history of rheumatic fever.
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