Testing For H1N1 Unnecessary In Most Cases

Ruzanna Harutyunyan's picture
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An update on novel H1N1 influenza (swine flu) issued by Dr. Don Williamson, State Health Officer, included the following information:

Novel H1N1 is widely prevalent in Alabama. Over the last four weeks, the Alabama Department of Public Health (ADPH) laboratory confirmed 652 cases of influenza, all of which were novel H1N1. Patients with flu-like symptoms most likely have H1N1 disease, and clinicians are justified in making this diagnosis based solely on presentation.

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Rapid influenza diagnostic tests positive for A or A/B are highly predictive of novel H1N1. H1N1 is less likely if the rapid test is positive for B. Negative rapid tests do not rule out H1N1. Several commercial laboratories offer H1N1 PCR testing, but routine confirmatory testing is not necessary and treatment decisions should not be delayed pending off-site test results.

Because of the widespread prevalence of the disease and finite capacity of the ADPH laboratory, ADPH must restrict testing to hospitalized patients, pregnant women, and a fixed number of patients seen weekly by a statewide network of designated practices. This approach will allow ADPH to confirm the diagnosis in severely ill persons and pregnant women and identify circulating influenza subtypes.

Although there have been a few case reports of resistance to Tamiflu, H1N1 is sensitive to both it and Relenza. H1N1 is resistant to adamantine and Flumadine. For maximum benefit, antiviral treatment should begin as close to the onset of illness as possible. Many persons with mild symptoms and no underlying risk factors for severe illness recover from H1N1 illness without taking antivirals.

The Centers for Disease Control and Prevention (CDC) says persons with influenza-like illness should remain at home until at least 24 hours after they are free of fever (100° F), or signs of a fever, without the use of fever-reducing medications. This is often three to five days. This recommendation applies to schools, businesses, mass gatherings, camps, and other community settings where the majority of people are not at increased risk for influenza complications. Because viral excretion can persist after cessation of fever, convalescent healthcare workers should remain at home for seven days from symptom onset or until the resolution of symptoms, whichever is longer.

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