Saturday, September 19, 2009

Flu tests- Fact and Fiction

How do you know if your flu is the H1N1 strain? Is there a quick test in the doctor's office?
Well, yes and no. Most primary care offices now have rapid flu tests in their offices that can tell you if you test positive for type A or type B influenza. If indeed you test positive for type A, at this point in the United States, you most likely have H1N1. 99% of samples of known positive type A flu that have been sent to the CDC are testing positive for H1N1. The difficulty is that the rapid flu tests are very specific (meaning if it is positive, you definitely have the flu) but not too sensitive (meaning if you do have the flu, there is a good chance - up to 30%- that the test will not show it.)
So, please understand that flu is primarily a clinical diagnosis. This means if you have high fever, intense headache, sore throat, cough, and body aches, and your doctor doesn't find evidence of any other disease (like strep throat or pneumonia), your doctor will likely conclude that you have influenza- whether or not she has the "proof" of a positive rapid test. It is also no longer necessary to send every positive type A flu test on to the CDC for confirmation that it is H1N1.
The good news is that H1N1 is proving to be primarily more mild than initially feared, and now treatment (meaning antiviral medicines) are only recommended for high risk groups (pregnant women, patients with poor immune systems as in cancer or HIV disease, young children under 5 or adults over 65, people with chronic diseases or people who are hospitalized.)
BOTTOM LINE: See your doctor and get tested if you think you have the flu, but understand the limitations of our current testing. Most importantly, remember GOOD HAND WASHING and STAY HOME if you have a fever!

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