Fever accounts for 30% of<unk>  visits
Children <3 months are immunocompromised (e.g. poor opsonization, poor IgG response to encapsulated bacteria, macrophage and neutrophil dysfunction, bone marrow insufficiency)
Serious bacterial illness (SBI) includes UTI, meningitis, pneumonia, bacteremia
7% of patients <2 years old with fever have pneumonia, however the etiology (viral/bacterial) or even the presence of pneumonia has low inter-observer reliability even among<unk>  radiologists
4% Prevalence of UTI with common other<unk> s of fever (OM, viral URI, etc)
0.3% of previously well children aged 3-36 months who have a fever without a<unk>  will develop significant sequelae, 0.03% will develop sepsis or meningitis
Relatively high coincidence of RSV, enterovirus, and paraflu with bacteremia (and UTIs), so positive lab test for these viruses should not change testing and management plan
RSV+ neonates aged 0-28 days, 3.7% were bactremic (and 6.1% had UTIs)
RSV+ infants aged 29-60 days, (5.5% had UTIs)
There is a low coincidence of influenza with SBI, so postivie lab test for this virus may change testing and management plan (i.e. lower risk of concurrent bacterial illness)
RSV+ neonates aged 0-28 days, 3.7% were bactremic (and 6.1% had UTIs)
RSV+ infants aged 29-60 days, (5.5% had UTIs)
Pediatric fever of uncertain source
Upper respiratory infection 
AIDS fever of unknown origin
UTI
Lemierre's syndrome
Sepsis
Multisystem inflammatory syndrome in children
Meningitis