eMedicine Specialties > Pediatrics: General Medicine > Infectious Disease

Fever Without a Focus

Author: Robert W Tolan Jr, MD, Chief, Division of Allergy, Immunology and Infectious Diseases, The Children's Hospital at Saint Peter's University Hospital; Clinical Associate Professor of Pediatrics, Drexel University College of Medicine
Contributor Information and Disclosures

Updated: Jan 22, 2009

Introduction

Background

Infants or young children who have a fever with no obvious source of infection present a diagnostic dilemma. Health care providers see these patients 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 proper diagnosis and management 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 occult bacteremia or other serious bacterial infections. Address the following questions:

• 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.

Pathophysiology

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. 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:

• Streptococcus pneumoniae
• Streptococcus agalactiae
• Neisseria meningitidis
• Haemophilus influenzae type b
• Listeria monocytogenes
• Escherichia coli

Historically, approximately 2.5-3% of highly febrile children younger than 3 years have occult bacteremia, which typically is caused by S pneumoniae. The advent of conjugate pneumococcal vaccine has resulted in a decrease in pneumococcal occult bacteremia and other disease.² Viral infections are common in the young child as well; however, exclude serious bacterial infection prior to assuming a viral etiology for the fever.

Frequency

United States

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

Mortality/Morbidity

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, this can cause morbidity or mortality.

Age

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

Clinical

History

Obtaining an accurate history from the parent or caregiver is important when assessing fever without a focus; the history obtained should include the following information:

• Fever history: What was child's temperature prior to presentation and how was temperature measured? Consider fever documented at home by a reliable parent or caregiver the same as fever found upon presentation. Accept parental reports of maximum temperature.
• Fever at presentation
  • If the physician believes the infant has been excessively bundled, and if a repeat temperature taken 15-30 minutes after unbundling is normal, the infant should be considered afebrile.
  • Always remember that normal or low temperature does not preclude serious, even life-threatening, infectious disease.
• Current level of activity or lethargy
• Activity level prior to fever onset (ie, active, lethargic)
• Current eating and drinking pattern
• Eating and drinking pattern prior to fever onset
• Appearance: Fever sometimes makes a child appear rather ill.
• Vomiting or diarrhea
• Ill contacts
• Medical history
• Immunization history (especially recent immunizations)
• Urinary output: Inquire as to the number of wet diapers.

Physical

While performing a complete physical examination, pay particular attention to assessing hydration status and identifying the source of infection. Physical examination of every febrile child should include the following:

• Record vital signs.
  • Temperature: Rectal temperature is the standard. Temperature obtained via tympanic, axillary, or oral methods may not truly reflect the patient's temperature.
  • Pulse rate
  • Respiratory rate
  • Blood pressure
• Measure pulse oximetry levels.
  • Pulse oximetry may be a more sensitive predictor of pulmonary infection than respiratory rate in patients of all ages, but especially in infants and young children.
  • Pulse oximetry is mandatory for any child with abnormal lung examination findings, respiratory symptoms, or abnormal respiratory rate, although keep in mind that the respiratory rate increases when children are febrile.
• Record an accurate weight on every chart.
  • All pharmacologic and procedural treatments are based on the weight in kilograms.
  • In urgent situations, estimating methods (eg, Broselow tape, weight based on age) may be used.
• 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 [OM], pharyngitis, sinusitis, skin or soft tissue infection)
  • Identifiable viral infection (eg, bronchiolitis, croup, gingivostomatitis, viral gastroenteritis, varicella, hand-foot-and-mouth disease)
  • Petechial or purpuric rashes, often associated with bacteremia
  • Purpura, which is associated more often with meningococcemia than is the presence of petechiae alone
• For all patients aged 3-36 months, management decisions are mostly based on the degree of toxicity and the height of temperature.
• The Yale Observation Scale is a reliable method for determining degree of illness.^3,4
  • It consists of 6 variables: quality of cry, reaction to parent stimulation, state variation, color, hydration, and response. A score of 10 or less has a 2.7% risk of serious bacterial infection. A score of 16 or greater has a 92% risk of serious bacterial infection.
  • Regarding the height of temperature, Hoberman et al found that 6.5% of patients with a temperature of 39.0°C (102.2°F) or more had a UTI and that white females with that temperature had a 17% incidence of UTI.⁵ In this age group, the prevalence of bacteremia correlates with the height of fever.
  • Children with temperatures from 39-39.5°C (102.2-103°F) have an approximate 2-4% risk of having occult bacteremia. Those with temperatures higher than 39.5°C (103°F) have an approximate 5% chance of having occult bacteremia.
  • The impact of the conjugated pneumococcal vaccine on these findings and predictions has not been evaluated.
  • Summary of the Yale Observation Scale
    
    

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    Table

    Observation Items	1 (Normal)	3 (Moderate Impairment)	5 (Severe Impairment)
    Quality of cry	Strong with normal tone or contentment without crying	Whimpering or sobbing	Weak cry, moaning, or high-pitched cry
    Reaction to parent stimulation	Brief crying that stops or contentment without crying	Intermittent crying	Continual crying or limited response
    Color	Pink	Acrocyanotic or pale extremities	Pale or cyanotic or mottled or ashen
    State variation	If awake, stays awake; if asleep, wakes up quickly upon stimulation	Eyes closed briefly while awake or awake with prolonged stimulation	Falls asleep or will not arouse
    Hydration	Skin normal, eyes normal, and mucous membranes moist	Skin and eyes normal and mouth slightly dry	Skin doughy or tented, dry mucous membranes, and/or sunken eyes
    Response (eg, talk, smile) to social overtures	Smiling or alert (<2 mo)	Briefly smiling or alert briefly (<2 mo)	Unsmiling anxious face or dull, expressionless, or not alert (<2 mo)

    Observation Items	1 (Normal)	3 (Moderate Impairment)	5 (Severe Impairment)
    Quality of cry	Strong with normal tone or contentment without crying	Whimpering or sobbing	Weak cry, moaning, or high-pitched cry
    Reaction to parent stimulation	Brief crying that stops or contentment without crying	Intermittent crying	Continual crying or limited response
    Color	Pink	Acrocyanotic or pale extremities	Pale or cyanotic or mottled or ashen
    State variation	If awake, stays awake; if asleep, wakes up quickly upon stimulation	Eyes closed briefly while awake or awake with prolonged stimulation	Falls asleep or will not arouse
    Hydration	Skin normal, eyes normal, and mucous membranes moist	Skin and eyes normal and mouth slightly dry	Skin doughy or tented, dry mucous membranes, and/or sunken eyes
    Response (eg, talk, smile) to social overtures	Smiling or alert (<2 mo)	Briefly smiling or alert briefly (<2 mo)	Unsmiling anxious face or dull, expressionless, or not alert (<2 mo)

Causes

• S pneumoniae
  • S pneumoniae is the leading cause of nearly all common bacterial upper respiratory tract infections (eg, pneumonia, sinusitis, OM).
  • This organism is the most common cause of meningitis in the United States, although the use of the pneumococcal vaccine will likely change this.
  • It is the most common cause of occult bacteremia, the incidence of which is decreasing.
• 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.

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