Influenza specimen collection
Corporate Authors:Centers for Disease Control and Prevention (U.S.)
Description:Nasopharyngeal swab -- Nasopharyngeal/nasal aspirate -- Nasopharyngeal/nasal wash -- Deep nasal swab -- Combined nasal & throat swab.
Desk reference guide.
• Label the specimen on viral transport media tube and ensure cap on tube is tightly sealed.
(Do not use a pencil or pen for labeling, as they can rub off or smear. Instead, use a bar code or permanent marker).
• Fill out paperwork in accordance with state health department guidelines.
• Include a frozen cold pack with the specimen(s).
• Pack specimens in accordance with U.S. Department of Transportation regulations regarding shipment of biological substances, see www.cdc.gov/flu/professionals/diagnosis/index.htm.
• Specimens should be placed into sterile viral transport media and immediately placed on refrigerant gel packs or at 4 degrees Celsius (refrigerator) for transport to the state public health laboratory.
• Keep specimens refrigerated (2-8 degrees Celsius, 26-46 degrees Fahrenheit) prior to shipping.
• Ship specimens for testing as soon as possible.
• If delivery will be delayed for more than 3-4 days, specimen should be frozen at -70 degrees Celsius (-94 degrees Fahrenheit).
• Ensure specimen will be received by the public health laboratory during normal business hours.
• A nasopharyngeal (NP) swab is the optimal upper respiratory tract specimen collection method for influenza testing. However, such specimens cannot be collected from infants and many older patients may not allow an NP specimen to be collected. Alternatively, a combined nasal and throat swab specimen or aspirate specimens can provide good influenza virus yield.
• Some influenza tests are approved only for use with certain kinds of respiratory tract specimens, so follow guidelines provided by test. Also, some tests (e.g., rapid influenza diagnostic tests) are only approved for certain kinds of respiratory tract specimens.
• For best results (i.e., highest influenza virus yield), collect respiratory tract specimens within four days of illness onset.
• Most sensitive and accurate tests for influenza virus detection are molecular or nucleic acid amplification tests (RT-PCR).
• Negative test results obtained from rapid influenza diagnostic tests (RIDTs) that detect influenza viral antigens do not exclude influenza virus infection in patients with signs and symptoms of influenza. A negative test result could be a false negative and should not preclude further diagnostic testing (such as RT-PCR) and starting empiric antiviral treatment.
• A surgical mask and gloves are recommended at a minimum for all procedures. For some patients and procedures, additional precautions may be indicated, see Standard Precautions at www.cdc.gov/hicpac/2007IP/2007ip_part4.html#a4.
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