Fast Five Quiz: Influenza

Michael Stuart Bronze, MD


November 06, 2018

The presentation of influenza virus infection varies; however, it usually includes many of the symptoms described below. Patients with influenza who have preexisting immunity or who have received vaccine may have milder symptoms. Onset of illness can occur suddenly over the course of a day, or it can progress more slowly over the course of several days. Typical signs and symptoms include (not necessarily in order of prevalence):

  • Cough and other respiratory symptoms

  • Fever

  • Headache

  • Myalgias

  • Nasal discharge

  • Red, watery eyes

  • Sore throat

  • Tachycardia

  • Weakness and severe fatigue

Cough and other respiratory symptoms may be initially minimal but frequently progress as the infection evolves. Patients may report nonproductive cough, cough-related pleuritic chest pain, and dyspnea. In children, diarrhea may be a feature.

The general appearance varies among patients who present with influenza. Some patients appear acutely ill, with some weakness and respiratory findings, whereas others appear only mildly ill. Upon examination, patients may have some or all of the following findings:

  • Fever of 100-104°F; fever is generally lower in elderly patients than in young adults

  • Tachycardia, which most likely results from hypoxia, fever, or both

  • Pharyngitis—Even in patients who report a severely sore throat, findings may range from minimal infection to more severe inflammation

  • Eyes may be red and watery

  • Skin may be warm to hot, depending on core temperature status; patients who have been febrile with poor fluid intake may show signs of mild volume depletion with dry skin

  • Pulmonary findings may include dry cough with clear lungs or rhonchi, as well as focal wheezing

  • Nasal discharge is absent in most patients

  • Fatigued appearance

For more on the presentation of influenza, read here.


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