Upper Respiratory Infection (URI)

Upper Respiratory Infection (URI) is a topic covered in the 5-Minute Clinical Consult.

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Basics

Upper respiratory infections (URIs) are one of the most common medical diagnoses, contributing to ~30 million office visits annually and resulting in significant lost productivity through missed days from work/school.

Description

  • Inflammation of nasal passages resulting from infection with respiratory viruses
  • Most cases are mild to moderate in severity, self-limited, and amenable to self-treat.
  • System(s) affected: ENT; pulmonary

Epidemiology

  • Each virus has different seasonal peaks (e.g., rhinovirus: late spring, fall); most infections occur during the winter months.
  • Symptoms usually peak in 1 to 3 days, lasting up to 2 weeks.
  • Transmission:
    • Contact with contaminated skin/surface followed by contact with mucous membranes (hand-to-face contact)
    • Aerosolized particles from sneezing and coughing
  • Viruses may last up to 2 hours on skin and even longer on environmental surfaces.

Incidence
  • Predominant age: children > adults
    • Preschool children: 5 to 7 URI per year
    • Kindergarten: 12 URI per year
    • Schoolchildren: 7 URI per year
    • Adolescents/adults: 2 to 3 URI per year
  • Predominant sex: male = female

Etiology and Pathophysiology

Rhinoviruses infect the ciliated epithelial mucosa of the upper airway, resulting in edema, hyperemia, and mucous production.

  • Histology: edema of subepithelial connective tissue and a scanty cellular infiltrate containing neutrophils, plasma cells, lymphocytes, and eosinophils with exudation of serous and mucinous fluid
  • Rhinovirus causes a “nondestructive” inflammation of the mucous membranes.
  • Influenza and parainfluenza viruses denude respiratory epithelium to the basement membrane.
  • Several hundred viral strains from different families; spread within geographic region and groups with close contact
    • Rhinovirus (>100 serotypes): 30–50%; incubation period 1 to 5 days
    • Influenza virus types A, B, C: 10–15%; incubation period 1 to 4 days
    • Coronaviruses: 10–15%
    • Parainfluenza, respiratory syncytial virus (RSV): 5%; more common in children; incubation period 1 week
    • Enteroviruses, adenoviruses: <10%
  • In many cases, no specific pathogen is identified.

Risk Factors

  • Exposure to infected people
  • Touching one’s face with contaminated fingers
  • Allergic disorders
  • Smoking
  • Immunosuppression
  • Stress

General Prevention

  • Frequent hand washing, especially in children
  • Limiting exposure to infected persons/children

Commonly Associated Conditions

  • Pharyngitis
  • Sinusitis
  • Otitis media
  • Bronchitis
  • Bronchiolitis
  • Pneumonia
  • Croup
  • Asthma

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