Sickle-cell disease patient over the age of 8
Absent spleen on CT
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Pneumonia
Sepsis/septicemia
Babesiosis, Ehrlichiosis
Infections from encapsulated bacteria (e.g. Strep pneumo, H. influenzae, Neisseria meningitidis)
Viral illnesses
Cough, fever, rigors, malaise
Nausea/vomiting, constipation/diarrhea
Urinary symptoms
wound infection
Rash
Increased oxygen requirement, tachycardia
Asplenic patient
Bacterial infection 
Combative patient
Streptococcus pneumonia
The obese patient
Haemophilus influenzae type B
Severe anemia in Jehovah's Witness patients
Neisseria meningitidis