1. SCARLET FEVER Dr. Mohamed Haseen Basha
Assistant professor ( Pediatrics)
Faculty of Medicine
Al Maarefa College of Science and Technology

2. SCARLET FEVER
Scarlet fever is an upper respiratory tract infection which is caused by an infection with pyrogenic exotoxin (erythrogenic toxin)–producing Group A β-hemolytic streptococcus.
3 Main clinical manifestations are :
Acute fever
Pharyngitis
Diffuse and red exanthematous rash followed by desquamation and hyperpigmentation
2~3weeks later :
Rheumatic fever
Glomerulonephritis
Arthritis

3. ETIOLOGY
Group A β-hemolytic streptococci Morphology and structure Gram-positive spherical cocci, Capsulated. Streptococcus groups: A~H & K~U on the basis of C-carbohydrate within the cell wall Group A : more than 80 immunologically distinct types that are based on differences in the M protein.

4. Epidemiology
Source of infection: Patients in scarlet fever or pharyngitis Carriers with streptococci in nasal and pharyngeal Route of transmission: Droplet, skin lesion, food, milk and water and so on. Susceptibility of population Depends up on Anti-bacterium immunity and Anti-pyrogenic toxin immunity

5. PATHOGENESIS
Pathogen -- Epithelial cells -- Diffusion in local tissue --Produces a large variety of extracellular enzymes and toxins, including erythrogenic toxins.
Hyaluronidase Streptodornase
M protein Streptokinase,
Capsule Streptolysin
Suppurative changes leads to
Pharyngitis, tonsillitis, Peritonsillar absces, Retropharyngeal abscess
Otitis media, Sinusitis
Impetigo, Pyoderma
Lymphangitis, lymphadenitis
Perianal cellulitis, Vaginitis, Septicemia, Pneumonia,
Endocarditis, Pericarditis, Osteomyelitis, Suppurative arthritis, Cellulitis, Omphalitis and Myositis.

6. Toxic change
pyrogenic exotoxin (erythrogenic exotoxin)
Fever, scarlatina rash and other toxic symptoms
Allergic reactive change
2~3weeks later,
Heart -- Rheumatic fever
Kidney -- Glomerulonephritis
Joint -- Arthritis
Reason: 1)similar antigen - crossed immune reaction
2)immune complex

7. Streptococcal pyrogenic exotoxins A, B, and C are responsible for the rash of scarlet fever and are elaborated by streptococci that contain a particular bacteriophage.
These exotoxins stimulate the formation of specific antitoxin antibodies that provide immunity against the scarlatiniform rash but not against other streptococcal infections.
GAS can produce up to 12 different pyrogenic exotoxins, and repeat attacks of scarlet fever are possible.

8. CLINICAL MANIFESTATION
Incubation period 2~3days(1~7days)
Characteristic clinical manifestations are :
Fever
Feature: persistent,
Temp : 39~40℃
Accompanied symptoms: Headache, Weakness, Poor appetite
Course: 1 week

9. PHARYNGITIS
Sore throat
tongue is usually coated and the papillae are swollen. After desquamation, the reddened papillae are prominent, giving the tongue a Bright red tongue – “strawberry color”

10. RASH
appears within hr after onset of symptoms, first signs of illness .It often begins around the neck and spreads over the trunk and extremities.
The rash is a diffuse, finely papular, erythematous eruption producing bright red discoloration of the skin, which blanches on pressure. It is often accentuated in the creases of the elbows, axillae, and groin.
The skin has a goose-pimple appearance and feels rough. The cheeks are often erythematous with pallor around the mouth. After 3-4 days, the rash begins to fade and is followed by desquamation, initially on the face, progressing downward, and often resembling a mild sunburn.
Peeling of the skin around the finger tips

12. DIAGNOSIS
History of close contact with a well-documented case of GAS pharyngitis Clinical data: Fever, Pharyngitis, Rash
Throat swab culture on a sheep blood agar plate has a sensitivity of 90-95% for detecting the presence of GAS in the pharynx. Is the gold standard test.
Rapid antigen detection tests : these rapid tests are more expensive than the blood-agar culture, the advantage they offer over the traditional procedure is the speed with which they can provide results, often less than minutes.
Nucleic acid amplification tests including isothermal loop amplification are also available to detect GAS pharyngitis.

13. DIFFERENTIAL DIAGNOSIS
MEASLES - Headache, malaise, coryza on the 1st day, Koplik’s spots the 2nd day, remains through the 3rd, 4th & 5th days. Rash comes out late on the 3rd or early on the 4th day.
RUBELLA - Little or no malaise, headache, slight fever, slight sore throat, the rash is out from 2nd to 3rd day. Spreads from above downwards. Look at the dorsum of the feet.
MENINGOCOCCEMIA - Within hours.
Y. PSEUDOTUBERCULOSIS - Apper on the 3rd and the 4th day. On the back of the head, neck, upper and lower extremities, nose and mouth triangle area.
DRUG RASH

14. COMPLICATIONS 2~3 weeks later Rheumatic fever Glomerulonephritis
Arthritis

15. TREATMENT
Group A streptococcus is exquisitely sensitive to penicillin, and resistant strains have never been encountered. Penicillin is, therefore, the drug of choice. Treatment with oral penicillin V for 10 days is recommended but it must be taken for a full 10 days even though there is symptomatic improvement in 3-4 days A single intramuscular injection of Benzathine penicillin G is the most efficacious and often the most practical method of treatment. Erytromycin for 10 days is the drug of choice for patients allergic to penicillin.