Fever without Localizing Signs

The list of microbes that cause fever in children is extensive. Relative importance of specific agents varies with age, season, and associated symptoms. The focus of this chapter is the febrile child with occult bacterial infection. Table 14-1 shows the most common causes of serious bacterial infection in children younger than 3 months. The division at 1 month is not absolute; considerable overlap exists. Also, certain viruses, notably herpes simplex and enteroviruses, can cause serious infections in neonates, mimicking septicemia. In children 3–35 months of age, most bacterial infections with no apparent focus are caused by Streptococcus pneumoniae (in unimmunized children), Neisseria meningitidis, or Salmonella spp. (the latter often occurring in association with symptoms of gastroenteritis). Haemophilus influenzae type b has become rare and incidence of Streptococcus pneumoniae infection has fallen substantially since universal administration of effective vaccines began. Other common causes of invasive bacterial infections, such as Staphylococcus aureus, are usually associated with identifiable foci of infection.