Evaluating fever of unidentifiable source in young children.

Most children will have been evaluated for a febrile illness by 36 months of age. Although the majority will have a self-limited viral illness, studies done before the use of Haemophilus influenzae type b and Streptococcus pneumoniae vaccines showed that approximately 10 percent of children younger than 36 months without evident sources of fever had occult bacteremia and serious bacterial infection. More recent studies have found lower rates of bacterial infection (1.6 to 1.8 percent). Any infant younger than 29 days and any child that appears toxic should undergo a complete sepsis work-up. However, nontoxic-appearing children one to 36 months of age, who have a fever with no apparent source and who have received the appropriate vaccinations, could undergo screening laboratory analysis and be sent home with close follow-up. Empiric intramuscular antibiotics are suggested for some children; however, cerebrospinal fluid studies should be obtained first. Because immunizations have recently decreased infection rates for S. pneumoniae and H. influenzae type b, the recommendations for evaluation and treatment of febrile children are evolving and could involve fewer tests and less-presumptive treatment in the future. A cautious approach should still be taken based on the potential for adverse consequences of unrecognized and untreated serious bacterial infection.