November 28, 2015

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Upper Respiratory Tract Infection

How is an upper respiratory infection diagnosed?

In evaluating people with suspected upper respiratory infection, other alternative diagnoses need to be considered. Some of the common and important diagnoses that can resemble upper respiratory infection are:

  • asthma,
  • pneumonia,
  • H1N1 (swine) flu,
  • influenza,
  • allergic reactions,
  • seasonal allergies,
  • chronic (long standing) sinusitis,
  • acute HIV infection, and
  • bronchitis.

The diagnosis of upper respiratory infection is typically made based on review of symptoms, physical examination, and occasionally, laboratory tests.

In physical examination of an individual with upper respiratory infection, a doctor may look for swollen and redness inside wall of the nasal cavity (sign of inflammation), redness of the throat, enlargement of the tonsils, white secretions on the tonsils (exudates), enlarged lymph nodes around the head and neck, redness of the eyes, and facial tenderness (sinusitis). Other signs may include bad breath (halitosis), cough, voice hoarseness, and fever.

Laboratory testing is generally not recommended in the evaluation of upper respiratory infections. Because most upper respiratory infections are caused by viruses, specific testing is not required as there is typically no specific treatment for different types of viral upper respiratory infections.

Some important situations where specific testing may be important include:

  • Suspected strep throat (fever, lymph nodes in the neck, whitish tonsils, absence of cough), necessitating rapid antigen testing (rapid strep test) to rule in or rule out the condition given possible severe sequelae if untreated.
  • Possible bacterial infection by taking bacterial cultures with nasal swab, throat swab, or sputum.
  • Prolonged symptoms, as finding a specific virus can prevent unnecessary use of antibiotics (for example, rapid testing for the influenza virus from nasal or pharyngeal swabs).
  • Evaluation of allergies and asthma which can cause long lasting or unusual symptoms.
  • Enlarged lymph node and sore throat as the primary symptoms that may be caused by Ebstein-Barr virus (mononucleosis) with expected longer time course (by using the monospot test).
  • Testing for the H1N1 (swine) flu if suspected.

Blood work and imaging tests are rarely necessary in the valuation of upper respiratory infection. X-rays of the neck may be done if suspected case of epiglottitis. Although the finding of swollen epiglottis may not be diagnostic, its absence can rule out the condition. CT scans can sometimes be useful if symptoms suggestive of sinusitis last longer than 4 weeks or are associated with visual changes, copious nasal discharge, or protrusion of the eye. CT scan can determine the extent of sinus inflammation, formation of abscess, or the spread of infection into adjacent structures (cavity of the eye or the brain). Continue Reading

Reviewed on 7/17/2015
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