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Fever of unknown origin in young infants

Author Prof. J. Spranger, University Department of Pediatrics Mainz

During a 13-year period a total of 2479 young infants (<3 months) were presented in a pediatric emergency unit with a history of fever [1]. To study the significance of fever itself, infants with clear clinical evidence of bacterial sepsis were eliminated from the retrospective study, as were infants with incomplete clinical data. This left a study group of 2470 infants who had fever at home but upon admission had no clinical signs suggesting a bacterial infection. The standardized management protocol included urine dipstick test, complete blood cell count, measurement of CRP, procalcitonin levels, blood and urine cultures. About a quarter of the patients were afebrile at admission. In this group of 678 well-appearing, afebrile infants sixteen (2.4%) had an invasive bacterial infection.  The incidence in infants with persisting fever was the same (43/1792 = 2.4%).


The practical conclusion from this finding is that fever in a young infant may signify an invasive bacterial infection, no matter if the fever has subsided or not. It will be diagnosed if the management protocol includes bacterial blood cultures. As suggested by the authors of the referred study, lumbar puncture may be limited to infants with clinical manifestations suggestive of meningitis. Urinary tract infection will be the most common cause of fever in a well-appearing young infant.

Minteg S. Gomez B, Carro A, et al. (2018) Invasive bacterial infections in young afebrile infants with a history of fever. Arch Dis Child 103:665-669.