Pediatric Influenza Clinical Presentation

Updated: Aug 16, 2022
  • Author: Itzhak Brook, MD, MSc; Chief Editor: Russell W Steele, MD  more...
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Typical symptoms of influenza begin 2-3 days after exposure to the virus. Influenza produces an acute febrile respiratory illness with cough, headache, and myalgia for 3-4 days, with symptoms that may persist for as long as 2 weeks. Similar symptoms can be seen in close contacts or family members.

Patients may present with sudden onset of the following:

  • High fever

  • Chills

  • Myalgia

  • Headache

  • Fatigue

Subsequent respiratory symptoms include the following:

  • Sore throat/pharyngitis

  • Nasal congestion

  • Rhinitis

  • Nonproductive cough

  • Cervical lymphadenopathy

  • Conjunctivitis

Conjunctivitis, rhinitis, and GI tract symptoms are more common in infants and young children than in adults.

In young infants, influenza may produce a sepsislike picture with shock; occasionally, influenza viruses can cause croup or pneumonia.

Avian influenza

Determine if the patient has a history of recent travel to countries where epidemics of avian influenza A/H5N1are reported. [34] If so, determine if the patient has a history of exposure to poultry from a region with an outbreak of highly pathogenic avian influenza A virus. They may be health care workers with exposure to infected patients. Poultry cullers with this infection have been reported. The incubation period of HP avian influenza A virus is typically 2-5 days but can be as long as 8-17 days. [21]

Avian influenza manifests with cough, respiratory distress, myalgia, conjunctivitis, diarrhea, and vomiting. Diarrhea can precede respiratory symptoms and is watery, without any inflammatory features. Occasionally, signs and/or symptoms of encephalitis may be noted upon presentation.


Physical Examination

Manifestations of influenza range from mild to severe. Fever, respiratory symptoms, and myalgia are typical. [40]

Patients with avian influenza A/H5N1 virus infection predominantly present with community-acquired pneumonia, conjunctivitis, and fever. Compared with patients who have seasonal influenza, patients avian influenza A virus tend to have fever more than 90% of the time, vomiting, pleurisy, abdominal pain, myalgia, sore throat, rhinorrhea, lymphadenitis, and nasal and gingival bleeding.

Patients with avian influenza can develop dyspnea within approximately 5 days from onset of illness. The sputum is occasionally bloody.


The following complications of seasonal influenza are noted:

  • Primary influenza viral pneumonia

  • Secondary bacterial pneumonia

  • Croup

  • Exacerbation of chronic pulmonary disease

  • Myositis

  • Myocarditis

  • Toxic shock syndrome

  • Guillain-Barré syndrome

  • Reye syndrome

Potential complications of avian influenza include the following:

Respiratory failure due to an ARDS-like picture reportedly occurs 4-13 days after onset of illness.