Febrile children < 1 month of age All febrile children < 1 month of age require a white blood cell (WBC) count with a manual differential, blood cultures, urinalysis and urine culture (obtained by catheterization, not an external bag), and cerebrospinal fluid (CSF) evaluation with culture and appropriate polymerase chain reaction (PCR) testing (eg, for herpes simplex, enterovirus) as indicated by historical risk factors.