Scarlet fever

Under the section of childhood infections, this is useful chart when parents ask – is this scarlet fever doc ? The easy to follow chart describes the aetiology, prevalence and pathophysiology of scarlet fever and investigations. Presentation of scarlet fever is followed by differential diagnosis. GPs should note that Phenoxymethypenicillin should be issued for 10 days and this is a notifiable disease. Complications can be suppurative and non-suppurative ( seen less now with use of antibiotics )

Caused by Group A beta-hemolytic streptococcus Gram positive cocci that grow in chains
 Classified by their ability to
 
○ produce hemolysis on blood agar 
 ♦ alpha-hemolytic – partial hemolysis 
 ♦ beta-hemolytic -complete hemolysis 
 ♦ gamma-hemolytic – no hemolysis 

○ by differences in carbohydrate cell wall component
 ♦ A-H and K-T
 Sometimes also called scarlatina ( older literature ) Notifiable disease in UK  Prevalence-Predominantly childhood disease Children between age 2-8 yrs with peak at 4 yrs Rarely before 2 yrs ( maternal antibodies and lack of sensitization ) Seasonal ( spring and winter months in UK ) Highly contagious Outbreak in overcrowded situations ( eg schools , situational settings ) Transmission – via aerosol droplets and direct contact Incubation period 2-3 days ( but can range from 1-6 days )

pathophysiology-Toxin mediated disease Exotoxins from strains of Streptococcus pyogens also known as Group A Streptococcus (GAS )
 Local production of inflammatory mediators and alteration of the cutaneous cytokine milieu
○ inflammatory response and dilatation of blood vessels –> scarlet color of rash
 GAS- can be normal commensal of upper resp tract in 3-23 % of normal children
 When GAS causes infection- primary site is usually throat causing – sore throat

Investigations-Throat swab and culture
○ has 90 % sensitivity
○ less specific
 Anti-streptococcal antibody titre
 Antigen detection kits
○ eg Rapid antigen detection test
 FBC
○ polymorphonuclear lymphocytosis is typical
○ eosinophilia may be seen during 2nd week

Presenting features-First features non specific
○ fever typically > 38.3
○ sore throat
○ headache , fatigue , nausea and vomiting
 Blanching rash –> develops an abdomen and chest 12-48 hrs after initial symptoms before spreading to neck , limbs and extremities
○ rash is diffuse , finely papular , erythematous
○ rash has red sandpaper like texture
○ florid in skin folds of neck , axillae , groin , elbows and knees
○ after 3-4 days rash begins to fade
○ skin may peel after rash resolves ( particularly tips of digits)
 Other possible features
○ strawberry tongue
 ♦ initially tongue covered with white coat through which papillae may be seen
 ♦ later white coat disappears leaving a beefy red tongue- strawberry or raspberry tongue
○ tender cervical lymphadenopathy
○ flushed face- circumoral pallor
○ pharyngitis- 
 ♦ red macules dotted over the hard and soft palate –> Forchheimer spots
 ♦ enlarged exudative tonsills
 Except for rash- symptoms similar as those of streptococcal pharyngitis

Differential-Rubella Parvovirus B19- Slapped cheek Measles Roseola infantum -Herpes virus type 6 Enterovirus and adenovirus Kawasaki disease Staphylococcal toxic shock syndrome

Rare causes
 Tropical viruses eg alphaviruses and flaviviruses ( Dengue fever ) Brucellosis , cytomegalovirus , HIV , syphillis , toxoplasmosis Drug reactions
Mononucleosis reaction to amoxicillin 
reaction to anti-epileptic drugs

Admission-Pre-existing valvular heart disease ↑ risk complications Immunocompromised ↑ risk complications Suspected severe complication of scarlet fever as
○ toxic shock syndrome
○ acute rheumatic fever
○ streptococcal glomerulonephritis

Treatment Phenoxymethylpenicillin ( Penicillin V ) 4/day for 10 days first line Amoxicillin is an alternative if for eg compliance is a concern Azithromycin for people allergic to penicillin
○ 12mg/ kg ( max 500 mg ) for childrem 6 mts to 11 yrs and 11 months
○ 500 mg if > 12 yrs and adults Paracetamol or Ibuprofen Rest and hydration Symptoms usually last no longer than 1 week Antibiotics will prevent complications Stay away from nursery , school or work for 24 hrs after starting antibiotic Hygiene measures and avoid sharing eating utensils and towels and dispose handkerchiefs properly Avoid contact with people with ↑ risk of complications of scarlet fever as
○ immunocompromized
○ skin lesions – as chicken pox or wounds
○ ♀ in puerperal period
○ comorbidities as diabetes Return if symptoms do not improve in after 7 days Beware of complications in 1st few weeks after infection
○ High risk contacts should seek urgent help if they develop any symptoms of GAS infection or its complications

Public health notification-Within 3 days Seek advice if a person is high risk contact- see above +
○ Injecting drug users
○ whether exclusions from work school or nursery and / or chemoprophylaxis

Complications-Suppurative –Due to spread to structures directly contagious to the pharynx -tend to occur early 
 Otitis media Throat infections and abscess
○ peritonsillar abscess
○ peritonsillar cellulitis
○ retropharyngeal abscess Acute sinusitis and mastoiditis Streptococcal pneumonia Meningitis and cerebral abscess Endocarditis , osteomyelitis and liver abscess Necrotizing fascitis and streptococcal toxic shock syndrome Non-suppurative-Tend to occur late and include
 Acute rheumatic fever
 Streptococcal glomerulonephritis
○ 2 weeks or more after infection
○ can present with
 ♦ haematuria
 ♦ ↓ urine output
 ♦ peripheral oedema
 ♦ proteinuria
 ♦ hypertension



 


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