Upper respiratory tract specimens are the preferred specimens for the diagnosis of influenza in outpatients with symptom duration of less than 4 days. Furthermore, nasopharyngeal specimens are preferred over other upper respiratory tract specimens for increased detection of influenza viruses. If it is not possible, nasal and throat swab specimens should be collected and combined together for influenza testing. If collection and combination is not possible, midturbinate nasal swab specimens are preferred over throat swab specimens. Flocking refers to the process of applying multilength fibers to an adhesive-coated surface. Flocked swab specimens are preferred over nonflocked swab specimens.
Reverse transcription polymerase chain reaction testing or viral culture of nasopharyngeal or throat secretions remains the criterion standard for confirming influenza virus infection. Culture may require 3-7 days, yielding results long after the patient has left the clinic, office, or emergency department and well past the time when drug therapy could be efficacious.
Collection of specimens from nonrespiratory sites such as blood, plasma, serum, cerebrospinal fluid, urine, and stool is usually not recommended.
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Cite this: Michael Stuart Bronze. Fast Five Quiz: Key Aspects of Influenza - Medscape - Mar 31, 2020.