Scarlet fever, which results from an
acute pharyngitis or tonsillitis caused by group A streptococci, is
characterized by a rash produced by the erythrogenic toxin.
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Streptococcal Infection
The incubation period of 2 to 5 days is
followed by chills and fever, fiery red pharyngeal mucosa, small crypt
abscesses in enlarged tonsils, and a bright red tongue with edematous
papillae ("raspberry tongue").
One to 3 days later there appears a
diffuse, punctate, erythematous rash, most prominent over the trunk
and inner aspects of the limbs and involving the face, except for a
small area around the mouth (“circumoral pallor”).
When the pharyngitis and rash subside,
near the end of the first week, desquamation begins.
Microscopically, an acute suppurative
exudate on the pharynx and oropharynx contains streptococci.
There is also an acute inflammatory
reaction in the lymph nodes.
Hyperkeratosis of the reddened skin
accounts for scaling during defervescence.
The characteristic 1 week duration of
scarlet fever is not shortened by antibiotic therapy, but suppurative complications, such as otitis media, sinusitis, and
mastoiditis, are prevented.
Scarlet fever is known for late nonsuppurative sequelae, which are also prevented by prompt treatment.
The precise
cause and pathogenesis of scarlet fever were not evident until the
Dicks demonstrated in 1924 that an erythrogenic toxin obtained from
broth filtrate of certain beta-hemolytic streptococci would , on
injection into a susceptible individual, produce a typical
erythematous reaction.
As a result of widespread application
of the Dick test, it became apparent that only a minority of adults
were susceptible to scarlet fever and that the number who were
“immune” was far greater than the number who had actually had the
disease previously.
Complications
of Scarlet fever are divisible into three major categories:
1. The results of
bacterial dissemination locally - otitis media, sinusitis, cervical
adenitis, acute suppurative mastoiditis, and retropharyngeal abscess.
2. The result of
bacterial dissemination generally - metastatic foci of infection
throughout the body or frank septicemia
3. The
manifestations of extraordinary reactions to toxins (this may be
brought about by hypersensitivity) - interstitial nephritis or
myocarditis,
pericarditis, nonsuppurative arthritis, and
glomerulonephritis.
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