Scarlet Fever - Causes, Symptoms and Treatments
Scarlet fever is an infectious disease caused by Group A beta-hemolytic streptococcal bacteria (GAS). The disease most commonly arises from tonsillar and pharyngeal infections, although it may follow streptococcal infections of the skin and soft tissue, surgical wounds (surgical scarlet fever), or the uterus (puerperal scarlet fever), making definitive diagnosis of scarlet fever difficult in these cases.
Considered a childhood disease, and formerly known as scarlatina, scarlet fever is a syndrome caused by exotoxins produced by GAS, and is characterized by a scarlatiniform rash. Over the past century, the number of cases of reported scarlet fever has remained high. Scarlet fever occurs predominately in children ages 5 to 15. The disease tends to be rare in children under age 2, likely because of acquired immunity from maternal antiexotoxin antibodies and lack of prior sensitization. By age 10, 80% of all children have developed life-long protective antibodies against streptococcal pyrogenic exotoxins.
Scarlet fever occurs year round, but the incidence of pharyngeal disease is highest in the winter and spring months. Up to 10% of GAS pharyngitis cases contract scarlet fever. Acquisition of the disease is high in over-crowded situations such as schools, childcare settings, hospitals, and areas of lower socioeconomic status. Today, due to the widespread use of antibiotics, scarlet fever runs a benign course with a death rate of less than 2%. Suppurative complications are the most common cause of death. Prognosis is excellent, with most patients having a full recovery.
Causes of Scarlet fever:
Most cases of scarlet fever are associated with GAS replication in the tonsillar and pharyngeal regions. GAS secretes a number of toxins, enzymes, and erythrogenic toxins. These erythrogenic toxins cause the rash of scarlet fever. The epidemiology of GAS is complex. Five separate and distinct streptococcal pyrogenic exotoxins (SPEs) have been described. Hypersensitivity to the exotoxins of GAS contributes to the susceptibility of contracting the disease. It is proposed that minor changes in the structure of the bacteria's DNA over time has caused GAS to become more invasive and severe, allowing it to mimic a virus. Transmission of the bacteria is most common via airborne respiratory particles. The incubation period for scarlet fever is 12 hours to 7 days, but persons infected are contagious during the acute illness and before the appearance of clinical signs and symptoms. Isolation of infected individuals is essential. Children should not return to school or day care settings until 24 hours of antibiotic therapy has been completed.
Signs and Symptoms of Scarlet Fever:
Most people who have contracted scarlet fever initially appear moderately wellpresenting with raw, red tonsils and pharynx with or without exudates. Other symptoms include fever, headache, abdominal pain, and vomiting.
The characteristic rash of scarlet fever appears 12 to 24 hours after the onset of the illness, first on the trunk then extending rapidly over the entire body to finally involve the extremities. It then becomes especially prominent in the skin folds of the axilla, groin, and buttocks, producing Patia's lines, which are lines of petechiae caused by increased capillary fragility. The rash consists of scarlet macules overlying generalized erythema. The erythema blanches with pressure. Between days 1 and 5, the rash eruptions become more palpable than visible, having the texture of coarse sandpaper or goose bumps. By day 3 to 4 after the onset of the rash, it will begin to fade and a desquamation period begins, with peeling of the face, palms, and fingers occurring between days 7 and 10. This phase can continue for up to 6 weeks, the extension and duration being directly related to the initial intensity of the rash.
The tongue also exhibits specific and characteristic signs and symptoms of scarlet fever infection. During the first 2 days, it will have a white coating through which red and edematous papillae project. This is called "white strawberry tongue". After 2 days, the tongue desquamates, resulting in a red tongue with prominent papillae, called "red strawberry tongue".
Although rare, complications may arise from scarlet fever infection, such as arthritis, bronchopneumonia, pericarditis, peritonsillar abscess, sinusitis, jaundice, otitis media, meningitis, cervieal lymphadenitis, brain abscess, and septicemia. Rare -but potentially fatal- complications include early toxin-related diagnoses, such as myocarditis and toxic shock syndrome. Late complications, such as rheumatic fever and glomerulonephritis, are associated with immune deficiency and may appear weeks to months after illness.
Diagnosis of Scarlet Fever:
Throat culture remains the definitive diagnostic tool for confirming a GAS upper respiratory infection. Throat cultures are about 90% sensitive for the presence of GAS in the pharynx. Direct antigen detection kits, also known as Rapid Antigen Tests (RATs), have been found to be sensitive only 50% to 90% of the time, and if the results are negative, a throat culture must he performed. With positive results, however, these RATs allow immediate diagnosis and prompt administration of antibiotics.
Serologic tests include streptococcal antibody tests to confirm recent GAS infection, but are not useful as a diagnostic tool during the acute phase of the illness. These tests include the Antistreptolysin O Titer (ASO) and the Streptozyme test.
Other conditions to consider include erythema multiforme, pediatric Kawasaki disease, pediatric measles, rubella, Rocky Mountain spotted fever, infectious mononucleosis, roseola, secondary syphilis, staphylococcal scalded skin syndrome, viral exanthema, Mycoplasma pneumoniae, exfoliative dermatitis, pediatric pharyngitis and pneumonia, scabies, toxic epidermal necrolysis, toxic shock syndrome, severe sunburn, and drug hypersensitivities.
Treatment of Scarlet Fever:
Treatment of scarlet fever involves a standard 10-day course of penicillin or erythromycin. Treatment of streptococcal infections is primarily focused on the prevention of acute renal failure from poststreptococcal glomerulonephritis. Acute renal failure is prevented even if antibiotic treatment is initiated 1 week after onset of acute pharyngitis. Supportive care would include hospitalization and I.V. therapy for those with difficulty swallowing secondary to throat pain and swelling.
Special considerations of Scarlet Fever:
1. Stress the importance of prompt and complete antibiotic therapy.
2. Teach the signs and symptoms of complications related to scarlet fever.
3. To maximize sensitivity of test results, throat cultures must be properly obtained.The posterior pharynx and tonsils and any exudates present should be swabbed vigorously with a cotton or Dacron swab under strong lighting to allow for maximum visualization. Caution should be maintained to avoid touching the swab to the lips, tongue, or buccal membranes to prevent contamination of the specimen.
4. Be aware that prior antibiotic therapy will alter tests, causing negative throat cultures and a delayed or negative ASO titer.
5. Care should be taken in disposing of all purulent drainage.
6. Offer comfort measures, such as acetaminophen or ibuprofen to relieve pain and reduce fever. Soothing gargles for adults and children who can gargle safely will help relieve sore throat pain. Cool mist humidifiers soothe breathing passages and throat discomfort. A liquid diet can be incorporated including warm soups and cool fluids for patients who are having difficulty swallowing.
7. Patients must be instructed on the importance of completing their entire course of antibiotic therapy, even if their symptoms have resolved. Patients should be warned that they will have generalized exfoliation over the course of the next 2 to 6 weeks.
8. Review the warning signs and symptoms for complications secondary to scarlet fever, such as persistent fever, increased throat or sinus pain, and generalized swelling (possible renal impairment) and the need for prompt reporting of these to a physician.
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