Influenza (cont.)

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How is the flu diagnosed?

The flu is presumptively diagnosed clinically by the patient's history of association with people known to have the disease and their symptoms listed above. Usually, a quick test (for example, nasopharyngeal swab sample) is done to see if the patient is infected with influenza A or B virus. Most of the tests can distinguish between A and B types. The test can be negative (no flu infection) or positive for types A or B. If it is positive for type A, the person could have a conventional flu strain or a potentially more aggressive strain such as H1N1. However, a new test developed by the CDC and a commercial company reportedly can detect H1N1 reliably in about one hour; the test was formerly only available to the military. In 2010, the FDA approved a commercially available test that could detect H1N1 within four hours. Most of the rapid tests are based on PCR technology.

Swine flu (H1N1) and other influenza strains like bird flu are definitively diagnosed by identifying the particular antigens associated with the virus strain. In general, this testing is done in a specialized laboratory and is not done by many doctors' offices or hospital laboratories unless they have purchased the newest test systems. However, doctors' offices are able to send specimens to specialized laboratories if necessary. Because of the large number of H1N1 swine flu cases that occurred in the 2009-2010 and 2010-2011 flu seasons, the vast majority of flu cases (about 95%-99%) were H1N1 flu viruses, the CDC has recommended only hospitalized patients' flu virus strains be sent to reference labs to be identified.

What is the key to flu prevention?

Flu vaccine

Most of the illness and death caused by influenza can be prevented by annual influenza vaccination. The CDC's current Advisory Committee on Immunization Practices (ACIP) issued recommendations for everyone 6 months of age and older, who do not have any contraindications to vaccination, to receive a flu vaccine each year.

Flu vaccine (influenza vaccine made from inactivated and sometimes attenuated [noninfective] virus) is specifically recommended for those who are at high risk for developing serious complications as a result of influenza infection.

A new vaccine type, Fluzone Intradermal, was approved by the FDA in 2011 (for adults 18-64 years of age). This injection goes only into the intradermal area of the skin, not into the muscle (IM) like most conventional flu shots and uses a much smaller needle than the conventional shots. This killed viral preparation is supposed to be about as effective as the IM shot but claims to produce less pain and fewer side effects (see section below).

Medically Reviewed by a Doctor on 2/20/2013

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Flu (Influenza) - Symptoms Question: Please describe your flu symptoms.
Flu (Influenza) - Side effects Question: Did you experience any side effects with the flu vaccine?

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