Influenza PCR Testing 2010-11
On Aug. 2, 2010 the clinical laboratories will begin performing PCR-based detection of influenza virus and respiratory syncytial virus (RSV). This test ("Influenza and RSV by RT-PCR") utilizes real-time reverse transcriptase-polymerase chain reaction (RT-PCR) to detect viral RNA.
This test detects influenza A (including 2009 (pandemic) H1N1, seasonal H1N1, and seasonal H3N2), influenza B, and RSV.
Currently there is no local influenza or RSV activity. Influenza activity remains low in the southern hemisphere1. The only circulating types are A:2009(pandemic)H1N1, A:H3N2, and B. Almost all of these strains are susceptible to oseltamavir.2
The RT-PCR assay is significantly more sensitive and more specific than rapid immunoassays (the sensitivity of the rapid influenza antigen test is approximately 30-50%) and is the preferred test for the diagnosis of influenza or RSV infections. Negative antigen tests need to be confirmed by RT-PCR.
Specimen collection Instructions for "Influenza and RSV by RT-PCR"
Collect a nasopharyngeal specimen using a flexible flocked nylon swab (manufactured by Copan). Do not use calcium alginate swabs which contain PCR inhibitors.
Insert the flocked nylon swab into a tube of M4 viral transport media (break off the handle at the molded breakpoint) and securely close the tube.
Send the tube to the laboratory as soon as possible. Duplicate tests cannot be ordered within 24 hours (or 3 days if influenza or RSV is detected).
The laboratory will shortly be offering RT-PCR tests for additional respiratory viruses. In the interim, if there is a clinical need to detect other respiratory viruses, collect an additional NP swab (if possible) in M4 media and order a viral culture.
1
Global Virological Surveillance (WHO Weekly Virological Update on 21 July 2010)(
http://www.who.int/csr/disease/swineflu/laboratory23_07_2010/en/index.html).2
MMWR. Update: Influenza Activity --- United States, 2009--10 Season. July 30, 2010 / 59(29);901-908(
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5929a2.htm?s_cid=mm5929a2_w)