Clinical Review

Unexplained fever in young children: how to manage severe bacterial infection

BMJ 2003; 327 doi: (Published 06 November 2003) Cite this as: BMJ 2003;327:1094
  1. Itzhak Brook, professor (
  1. 1Department of Pediatrics, Georgetown University School of Medicine, Washington, DC 20057, USA
  1. Correspondence to: 4431 Albemarle St NW, Washington DC 20016, USA

    Fever with no clear source of infection in children under 3 years old carries a small but important risk of sepsis and meningitis. This review describes the bacterial causes of such infection and the appropriate management in different age groups


    Fever in infants has been defined as a rectal temperature of 38°C (100.4°F) or higher. In older children, a rectal temperature of 38.4°C (101.1°F) or an oral temperature of 37.8°C (100°F) is generally considered abnormal.1 Most young children with fever and no focus of infection present with a self limiting viral illness that does not need any treatment and disappears without sequelae. Urinary tract infection is another important cause of fever in young children who are febrile with no focus of infection.2 However, a few children may eventually develop occult bacteraemia that may be associated with serious bacterial infection. Multiple studies have tried to identify children who seem well but have a serious infection and to evaluate the potential treatments. This review discusses the bacterial causes, essential diagnostic tests, clinical assessment, judicious use of antibiotics, and follow up in unexplained, difficult to diagnose bacterial infection causing fever in young children.

    Sources and selection criteria

    I gathered information by searching Medline, using personal archives, and reading relevant literature. The review and recommendations are based on observational studies and systematic reviews.


    Many organisms can cause febrile occult infection in young children. Their distribution is seasonal and varies in different age groups. Substantial overlap exists, however (box 1).

    The main bacterial causes of infection in children aged under 1 month are listed in box 1. Viral agents (mostly Herpes simplex and enteroviruses) can also cause life threatening febrile infection in this age group.3 Most infections in children over 3 months are caused by Streptococcus pneumoniae (in non-immunised children), Neisseria meningitidis, or Salmonella spp. Staphylococcus …

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