Scarlet fever

Pediatric Infectious Diseases

1. Scarlet Fever Shyala Chand Group 3

2. Introduction Scarlet fever is a bacterial illness that often presents with a distinctive rash. In the past, scarlet fever was thought to reflect infection of an individual lacking toxin-specific immunity with a toxin-producing strain of GAS. Subsequent studies have suggested that development of the scarlet fever rash may reflect a hypersensitivity reaction requiring prior exposure to the toxin. Has also been called scarlatina in the past.

3. Etiology G roup A beta- haemolytic streptococcus bacteria. S treptococci are gram-positive, spherical to ovoid bacteria. Most streptococci that cause human infections are facultative anaerobes. The rash arises from the effects of one of several toxins, currently designated streptococcal pyrogenic exotoxins and previously known as erythrogenic or scarlet fever toxins.

4. Epidemiology Scarlet fever occurs mostly in children aged 4-8 years. Scarlet fever generally has a 3-6 day incubation period (1-7 days). Common in late winter and early spring By 10 years old, up to 80% of children have developed lifelong protective antibodies against streptococcal toxins, whilst children younger than 2 years still have acquired maternal anti-exotoxin antibodies. Males and females are affected equally.

5. T ransmission Group A streptococcal infections that cause scarlet fever are contagious. Streptococcal bacteria can spread from person to person by breathing in airborne droplets from an infected person's coughing or sneezing. Bacteria can also be passed by touching the infected skin of someone with a streptococcal skin infection, or by sharing contaminated clothes, towels or bed linen. Scarlet fever can also be spread by infected individuals who are carriers of streptococcal bacteria but do not show any symptoms. Up to 15-20% of school-age children are thought to be asymptomatic carriers.

6. Cont’d To get scarlet fever you must still be susceptible to the toxin produced by the streptococcal bacteria. Therefore , it can happen that 2 children of the same family may both have streptococcal infections, but only one (who is still susceptible to the toxin) develops scarlet fever . It affects people who have recently had a sore throat (strep throat) or school sores (impetigo) caused by certain strains of the group A streptococcus

7. Risk Factors G reatest risk for scarlet fever include : People living in overcrowded environment such as boarding schools, day care or military camps. Children older than 3 years. People in close contact with someone who has a strep throat or skin infection .

8. Pathogenesis Adhere to epithelial cells in pharynx via F Protein. Extracellular Products: S treptolysins S and 0 - toxins that damage cell membranes and account for the hemolysis produced by the organisms; S treptokinase DNAses SpyCEP - a serine protease that cleaves and inactivates the chemo-attractant cytokine interleukin 8, thereby inhibiting neutrophil recruitment to the site of infection S everal pyrogenic exotoxins – produce characteristic rash and fever.

9. Typical Clinical Manifestations Incubation period is usually 3-6 days (1-7 days). The onset is abrupt with fever, headache, dysphagia, vomiting, with approximately 3 days duration. The fever can reach values of 39°-40°C and is often preceded by shivers and tachycardia. In infants and young children the symptoms can be also accompanied by seizures. Exanthem Filatov’s mask - circumoral pallor Pastia’s lines - accentuation of the rash in skinfolds. Generalized rash- approx. 24hrs after onset. Begins on trunk and spreads to extremities. Minute papules， give a characteristic "sandpaper" feel to the skin . Blanch when pressure is applied. The erythema abates in 7-9 days . Desquamation period starts after 7-14 days of illness

10. Generalized Rash Filatov’s Mask Pastia’s Lines Desquamation

11. Cont’d Enanthem consists of: Characteristic appearance of tongue Exudative or erythematous pharyngitis and tonsillitis , and very rarely, ulcerative aspect of tonsillitis. “Strawberry Tongue” - enlarged papillae on a coated tongue, which later may become denuded

12. Differential Diagnosis Measles Rubella Drug induced exanthema Erythema Infectiosum (Parvovirus B19) EBV Roseola Infantum

13. Diagnosis Clinical diagnosis supported by lab investigations. Throat or nasal culture or rapid streptococcal test. Serologic : positive for   antistreptolysin -O titers and Anti- dexoyribonuclease B. CBC : leukocytosis , neutrophilia , high ESR, and C-Reactive protein.

14. Treatment

15. Complications Rheumatic fever Otitis media Pneumonia Septicaemia Glomerulonephritis Osteomyelitis

16. Prevention Isolation! Maintain sanitation.

17. Thank you