What type of fever is typically associated with bronchiolitis?

Fever Patterns in Bronchiolitis

Bronchiolitis is typically associated with a low-grade fever, though some children may present without fever or with high fever depending on the viral etiology and individual factors. 1, 2

Clinical Presentation of Fever in Bronchiolitis

• Bronchiolitis is a clinical diagnosis characterized by tachypnea, wheeze and/or crackles in children under 2 years following an upper respiratory illness 3
• Initial symptoms typically include rhinitis and cough, which may progress to lower respiratory symptoms, often accompanied by low-grade fever 4, 2
• After an incubation period of four to six days, symptoms begin with rhinorrhea, congestion, sneezing, and fever before progressing to lower respiratory tract involvement 2
• Fever is not always present in bronchiolitis, and its absence does not rule out the diagnosis 3

Fever Patterns by Age

• In infants 1-12 months, fever may be present but respiratory symptoms (tachypnea, nasal flaring, intercostal retractions) typically dominate the clinical picture 1
• Younger infants (under 12 weeks) are at higher risk for severe disease and may present with more pronounced fever 3, 1
• In children 12-24 months, fever typically accompanies the initial upper respiratory symptoms before progression to wheezing and rales 1

Fever Patterns by Viral Etiology

• Respiratory Syncytial Virus (RSV), the most common cause of bronchiolitis (60-80% of cases), may present with variable fever patterns 4, 5
• Other viruses causing bronchiolitis include:
  • Human metapneumovirus 4
  • Influenza virus (often associated with higher fevers) 4
  • Adenovirus (may cause higher, more persistent fevers) 4
  • Parainfluenza viruses 4
  • Rhinovirus (often associated with milder disease and lower fevers) 6

Risk Factors for More Severe Disease and Fever

• Infants younger than 12 weeks 3
• History of prematurity, especially those born before 32 weeks gestation 3, 1
• Underlying cardiopulmonary disease 3, 7
• Immunodeficiency 3, 1
• Neuromuscular disease 1

Clinical Course of Fever

• Bronchiolitis is typically self-limiting, with most children recovering within 2-3 weeks 3
• Fever usually resolves within the first few days of illness 2
• 90% of children are cough-free by day 21 (mean time of cough resolution is 8-15 days) 3
• Children with persistent symptoms beyond 4 weeks may represent a different clinical problem, sometimes termed "post-bronchiolitis syndrome" 3

Management Considerations

• Treatment of bronchiolitis, including associated fever, is mainly supportive 2, 5
• Antipyretics may be used for comfort but do not alter the disease course 2
• Antibiotics are not routinely recommended unless there is clear evidence of bacterial co-infection 2, 8
• When fever persists beyond the expected timeframe or is unusually high, clinicians should consider alternative diagnoses or complications 3

Important Caveats

• Fever patterns alone cannot reliably distinguish between viral etiologies of bronchiolitis 2
• High or persistent fever may suggest secondary bacterial infection or alternative diagnosis 7
• The absence of fever does not rule out severe bronchiolitis, particularly in very young or premature infants 1, 7