Fever Without a Focus

Updated: Jun 22, 2023
  • Author: Muhammad Waseem, MBBS, MS, FAAP, FACEP, FAHA; Chief Editor: Russell W Steele, MD  more...
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Practice Essentials

Fever without a focus is an acute febrile illness in an infant or young child in which the cause is not apparent after a history is obtained and a physical examination is performed. [1]  Fever is defined as a rectal temperature that exceeds 38°C (100.4°F). For all patients aged 2-36 months, management decisions are based on the degree of toxicity and the identification of a serious bacterial infection.

Signs and symptoms

During the examination, concentrate on identifying any of the following:

  • Toxic appearance, which suggests possible signs of lethargy, poor perfusion, hypoventilation or hyperventilation, or cyanosis (ie, shock)
  • A focus of infection that is the apparent cause of the fever
  • Minor foci (eg, otitis media, pharyngitis, sinusitis, skin or soft tissue infection)
  • Identifiable viral infection
  • Petechial or purpuric rashes, often associated with bacteremia
  • Purpura, which is associated more often with meningococcemia than is the presence of petechiae alone

See Presentation for more detail.


Recommended testing for children with fever without a focus is based on the child’s appearance, age, and temperature. [2]

Perform the following for children who do not appear toxic:

  • Urinalysis by bladder catheterization and urine culture based on the following criteria: all males younger than 6 months and all uncircumcised males younger than 12 months; all females younger than 24 months and older female children if symptoms suggest a urinary tract infection
  • Rapid testing for viruses (eg, influenza, respiratory syncytial virus), which may be useful to decrease the need for other studies and/or antibiotic therapy
  • A fecal white blood cell (WBC) count and a stool guaiac test in patients with diarrhea
  • Complete blood cell (CBC) count and blood culture in unimmunized patients

Perform the following for children who appear toxic:

  • A CBC count with manual differential
  • Blood cultures
  • Chest radiography for patients with a WBC count greater than 20,000/μL
  • Urinalysis by bladder catheterization and urine culture based on the criteria listed above
  • Lumbar puncture and cerebrospinal fluid culture
  • A fecal WBC count and a stool guaiac test in patients with diarrhea
  • Rapid testing for viruses (eg, influenza, respiratory syncytial virus), which may be useful to decrease the need for other studies and/or antibiotic therapy

See Workup for more detail.


Treatment recommendations for children with fever without a focus are based on the child's appearance, age, and temperature.

For children who do not appear toxic, treatment recommendations are as follows:

  • Schedule a follow-up appointment within 24-48 hours and instruct parents to return with the child sooner if the condition worsens
  • Hospital admission is indicated for children whose condition worsens or whose evaluation findings suggest a serious infection

For children who appear toxic, treatment recommendations are as follows:

  • Admit child for further treatment; pending culture results, administer parenteral antibiotics
  • Initially administer ceftriaxone, cefotaxime, or ampicillin/sulbactam (50 mg/kg/dose)

See Treatment and Medication for more detail.



Infants or young children who have a fever with no obvious source of infection present a diagnostic dilemma. Health care professionals commonly evaluate children with fever on a daily basis. As many as 20% of childhood fevers have no apparent cause. [1] A small but significant number of these patients may have a serious bacterial infection; the risk is greatest among febrile infants and children younger than 36 months, making accurate diagnosis and management planning important. Physical examination and patient history do not always identify patients with occult bacteremia or serious bacterial infection. Serious infections that are not recognized promptly and treated appropriately can cause significant morbidity or mortality.

This article focuses primarily on infants and young children aged 2-36 months and reflects the significant changes in the care of the febrile infant and child over the past 10 years. The article Fever in the Young Infant addresses the diagnosis and treatment of febrile infants younger than 2 months.

Fever is defined as a rectal temperature that exceeds 38°C (100.4°F). Direct the initial evaluation of these patients toward identifying or ruling out serious bacterial infections (SBI), most commonly urinary tract infections. The following questions are important to consider:

  • What laboratory studies are indicated for various age ranges?

  • Which patients need in-depth evaluation and treatment?

  • Which patients need treatment with antibiotics?

  • Which patients should be hospitalized?

  • Which patients can be sent home safely and what follow-up is appropriate for them?

  • Are the diagnosis and treatment modalities for each patient cost-effective?

  • What is the potential morbidity associated with testing and treatment?

  • What are the parental (and patient) preferences for testing and treatment?

A great deal of time and effort has been spent on research to help identify the febrile infant and young child with a serious bacterial infection. However, evaluation and treatment of febrile infants and young children vary, despite nationally published treatment guidelines.

Note also, this article primarily addresses children who are completely immunized, and in particular who have received full Hib and PCV7 vaccine series. Unimmunized children are at higher risk for bacteremia, pneumonia, and other SBIs.



Meningitis, pneumonia, urinary tract infection (UTI), and bacteremia are serious etiologies of fever in infants and young children.

Neonates' immature immune systems place them at greater risk of systemic infection. Hematogenous spread of infection is most common in this age group or in patients who are immunocompromised or unimmunized. For these same reasons, infants who have a focal bacterial infection have a greater risk of developing metastatic infection or bacteremia.

The following are among the most common bacterial etiologies of serious bacterial infection in this age group:

Historically, approximately 2.5-3% of highly febrile children younger than 3 years have occult bacteremia, which is typically caused by S pneumoniae. [3] The advent of conjugate pneumococcal vaccine has resulted in a decrease in pneumococcal occult bacteremia and other disease. [4] Viral infections are common in the young child as well [5] ; however, exclude serious bacterial infection prior to assuming a viral etiology for the fever. [6]



Several common bacteria cause serious bacterial infections, including the following:

  • S pneumoniae: S pneumoniae is still the leading cause of nearly all common bacterial upper respiratory tract infections (eg, pneumonia, sinusitis, otitis media). This organism is also still the most common cause of meningitis in the United States, despite use of the conjugate pneumococcal vaccine. [7]

  • N meningitidis

  • H influenzae type b

  • L monocytogenes

  • E coli: E coli is the most common cause of UTIs. Among febrile children with UTIs, 75% have pyelonephritis, with consequences that, if missed, include renal scarring in 27-64% of patients, a 23% risk of hypertension, a 10% risk of renal failure, and a 13% risk of preeclampsia as adults. Approximately 13-15% of end-stage renal disease is believed to be related to undertreated childhood UTIs.

  • Salmonella



United States statistics

Fever accounts for 10-20% of pediatric visits to health care providers.

Race-, sex-, and age-related demographics

There is no racial difference in incidence of fever.

There is no difference in incidence of fever in males versus females.

This article focuses on the diagnosis and treatment of febrile children aged 2-36 months.



The prognosis for an appropriately treated patient is excellent.


Patients with no easily identified source of infection have a small but significant risk of a serious bacterial infection. If not recognized and treated appropriately and promptly, a serious bacterial infection can cause morbidity or mortality.


Although almost all infants, toddlers, and young children with fever without a focus have benign, viral infections, a small number may have serious bacterial infection, which makes good follow-up all the more important.


Patient Education

For patient education resources, see the following WebMD articles: