Download Scarlet fever

Scarlet fever
Introduction
1 A kind of acute infectious
disease of respiratory tract
2 Group A β-hemolytic
streptococcus
3 Main clinical manifestation:
acute fever
pharyngitis
diffuse and red exanthem(rash)
desquamation and hyperpigmentation
*******
2~3weeks later
rheumatic fever
glomerulonephritis
arthritis
Etiology
Group A β-hemolytic streptococci
1 Morphology and structure
Gram-positive spherical cocci
Diameter: 0.6~1.0 μm
Capsule(+) flagellum and spore(-)
Streptococcus groups: A~H & K~U on the basis of Ccarbohydrate within the cell wall
Group A : more than 80 immunologically distinct types
that are based on differences in the M protein.
2 Pathogenecity
M protein: resists phagocytosis
the major virulence factor
to neutrophils and platelets
Capsule: resist phagocytosis
Lipoteichoic acid: another
virulence factor
bind to fibronectin on
the surface of
epithelial cells
Pyrogenic toxin: produce rash, fever
resist phagocytosis,
promote Schwartzman
reaction
Streptokinase
Streptodornase
Streptolysin O & S: WBC, RBC & platelet
Hyaluronidase: hyaluronic acid
Epidemiology
1 Source of infection:
Patients in scarlet fever or
pharyngitis
Carriers with streptococci in nasal and
pharyngeal
2 Route of transmission:
droplet, skin lesion, food, milk
and water and so on.
3 Susceptibility of population
Anti-bacterium immunity anti-M
Anti-pyrogenic toxin immunity
4 The feature of epidemiology
season, age, endemic area, variation of this disease*
Pathogenesis
1 Suppurative change
Pathogen----epithelial cells----diffusion in local tissue
LTA
hyaluronidase
M protein
streptokinase, streptodornase
capsule
streptolysin
-----------suppurative change
pharyngitis, tonsillitis
peritonsillar abscess
retropharyngeal abscess
otitis media, sinusitis
lymphangitic-----lymphadenitis
bacteremia(sepsis, osteomyelitis,
pneumonia)
2 Toxic change
pyrogenic exotoxin (erythrogenic exotoxin)
fever
scarlatina rash
other toxic symptoms
3 Allergic reactive change
2~3weeks later,
Heart-------rheumatic fever
Kidney-----glomerulonephritis
joint---------arthritis
reason: 1)similar antigen----crossed immune
reaction
2)immune complex
Clinical manifestation
Incubation period 2~3days(1~7days)
Character of clinical manifestation:
Fever Pharyngitis scarlatina rash
1 Fever
1) feature: persistent,
fever & rash*
2) tem. : 39~40℃
3) accompanied symptoms:
headache, weakness, poor appetite
4) course: 1 week
2 Pharyngitis
symptom
sign
3 Rash
1) fever & rash**: 24 hours
2) initial position: ear , neck, upper chest
3) feature: diffuse papular(punctate or finely)
miliary sudamina (not so many)
circumoral pallor
strawberry tongue
red strawberry tongue
Pastia lines(antecubital fossate)
desquamation and hyperpigmentation
Type of clinical manifestation
light type
toxic type
sepsis type
surgery type
obstetrics type
Laboratory examination
1 peripheral picture: WBC, neutrophil 80%
2 Urine allergic reaction : protein RBC,
WBC, cylindruria
3 bacteriology test: Immunological
fluorescence
assay(IFA)
bacteria culture
Complication
2~3 weeks later
rheumatic fever
glomerulonephritis
arthritis
Diagnosis
1 clinical data: fever, pharyngitis, rash
2 laboratory test: peripheral picture,
Urine
Bacteriology test
Dick test ( pyrogenic test)
3 epidemiology data
Differential diagnosis
1 staphylococcus infection
2 drug rash
3 Virus rash
measles, rubella etc.
Treatment
1 penicillin adult: 80万U/ time, bid 5~7days.
child:20万U/(kg d), 10days
800万U/d(adult)
2 erythromycin
Prevention
1 Isolation: patients in scarlet
fever
2 protection: