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Each year, a large number of children are evaluated by their
primary care physicians for recurrent infections, an especially
common event in early childhood.1 The overwhelming
majority of such cases are benign, and an extrinsic cause of recurrent
infection is identified. Examples of extrinsic causes include heightened
exposure to pathogens in a daycare setting, carriage of a pathogenic
organism such as Staphylococcus aureus in the context
of recurrent infection with this organism, or recurrent upper respiratory
tract infections in the context of parental smoking. However, concern
about an intrinsic pathologic underpinning is heightened on the
basis of frequency of infections, their severity, and the nature
of the offending organism. The coexistence of multisystem disease,
autoimmunity, or lymphoreticular malignancy should also prompt evaluation for
immunodeficiency. A family history of recurrent infections raises the
index of suspicion.
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One helpful clue to the presence of a host abnormality is a high
frequency of infections. Examples include two or more systemic bacterial
infections at any time (such as sepsis, deep-seated abscesses, or
meningitis), three or more bacterial infections (eg, draining otitis media),
or six to eight or more upper respiratory tract infections in 1
year.2 The last finding should be modified by the
fact that many children, especially toddlers, suffer from recurrent upper
respiratory tract infection from repeat exposure to respiratory
(usually viral) pathogens, especially during the first year of daycare
attendance.
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Recurrent infections with a particular organism also point to
abnormalities of the host. A case in point is meningococcemia, in
which a second episode of this disease raises the prevalence of
a terminal complement pathway abnormality in afflicted individuals
from ⩽1% to 30 to 40%. Other examples include Staphylococcus
aureus infections in children with chronic granulomatous
disease (CGD) or leukocyte adhesion deficiency (LAD).
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The severity of the recurrent infection is reflective of the
seriousness of the underlying disorder. The compromised child may
fail to recover completely between infections. Failure to thrive,
weight loss, and growth retardation are grave manifestations of immunodeficiency
and call for immediate investigation. The need for surgical intervention provides
yet another measure of the severity of the underlying infection.
Such interventions may include myringotomy tube placement for chronic
otitis media, sinus surgery for chronic sinusitis, lobectomy for
chronic right middle lobe pneumonia, and drainage of superficial and
deep abscesses.
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The availability of effective antibiotic therapy may modulate
the presentation, but in general the clinical picture may slowly
but progressively worsen over a protracted period of time.
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The nature of sites affected by the recurrent infections also
provides valuable clues to the problem at hand. Humoral immunodeficiency, cystic
fibrosis, and immotile cilia syndrome result in recurrent severe
sinopulmonary infections including chronic sinusitis, pneumonia, and
bronchiectasis. Humoral immunodeficiency may also result in chronic
diarrhea as a consequence of infestations with pathogens such as Giardia
lamblia. Recurrent infections affecting one particular
site (eg, one specific lung lobe or one ear) may ...