What are the CDC recommendations for avian influenza A (H7N9) testing?

Updated: Apr 23, 2019
  • Author: Hien H Nguyen, MD, MS; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

In a June 7, 2013 Health Update, the CDC recommended that only patients who meet specific exposure criteria and have respiratory illness severe enough to require hospitalization should be tested for avian influenza A (H7N9). The recommendations include the following [48, 49] :

  • Clinicians should consider H7N9 testing by reverse-transcription polymerase chain reaction (RT-PCR) assay for patients who meet both clinical criteria (new onset of acute respiratory infection that is severe enough to require hospitalization, and lack of identification of an alternative infectious etiology) and exposure criteria (travel within 10 days of symptom onset to areas with known human cases of H7N9 infection or to areas where H7N9 viruses are circulating in animals, or close contact with confirmed human cases of H7N9 infection)

  • In cases in which human H7N9 infection is suspected on the basis of current screening recommendations, respiratory specimens should be collected using infection precautions for novel virulent influenza viruses; the swab or aspirate should be placed in viral transport medium, and the state or local health department should be contacted to arrange transport to the appropriate health department for testing (viral culture should not be performed in these cases)

  • Rapid influenza diagnostic tests may not identify H7N9 in respiratory specimens, and a negative test result does not exclude H7N9 infection; in addition, a positive test result for influenza A is unable to distinguish between influenza A virus subtypes, so it cannot confirm avian influenza virus infection; respiratory specimens should be obtained and sent for RT-PCR assay at a state public health laboratory when rapid influenza diagnostic tests are positive for influenza in patients suspected of having novel influenza A virus infection


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