Swine-origin Influenza A Virus: Interim Guidance for Intensivists, Hospitalists, Pulmonologists, and Infectious Disease Practitioners
(May 10, 2009)
As of May 10, 2009, the Centers for Disease Control and Prevention reported 2,532 confirmed cases of swine-origin Influenza A virus (SOIV) in the United States.
Most people do not have immunity to this new virus; as a result, widespread infection is possible. To date, clinical illnesses have been described as mild but there have been sporadic reports of persons requiring mechanical ventilation. Currently, the Washington State Department of Health (DOH) and local health jurisdictions are developing plans for case testing and disease surveillance. A major goal of this surveillance will be to determine if this novel virus becomes more virulent.
DOH is asking intensivists, pulmonologists, hospitalists, and infectious disease practitioners to report cases of severe respiratory illness defined as:
· Hospitalized persons with
· Community-acquired illness (respiratory illness ≤ 48 hours of admission) AND
· Adult Respiratory Distress Syndrome, Acute Lung Injury, moderate to severe hypoxia, respiratory failure, or pneumonia AND
· Presence of fever, hypothermia, or sepsis suggesting an infectious etiology; AND
· No other medical explanation for the presentation.
Persons with staphylococcal pneumonia should also be considered in this group.
When these cases are identified, please do the following to identify if influenza virus is present:
- Confirm that infection control measures are in place. Use standard and contact precautions when collecting the specimens. In addition, wear an N95 respirator when performing a procedure which could result in an infectious aerosol.
- Obtain a nasopharyngeal specimen using a synthetic swab (not cotton or calcium alginate) and place in viral transport medium. This specimen should be refrigerated (not frozen).
- For intubated patients, collect a tracheal specimen and sample the aspirated material using the same type of swab described above. Place in viral transport medium and refrigerate (do not freeze).
- Perform a rapid test for influenza A. If positive, contact your local public health jurisdiction and ship a second swab with a completed virology form (http://www.doh.wa.gov/EHSPHL/PHL/Forms/SerVirHIV.pdf) to: Washington State Public Health Laboratories, Attention: Virology Lab, 1610 NE 150th Street, Shoreline, WA 98155. This will be tested for SOIV.
- For rapid test-negative persons, consider performing additional influenza testing if you still suspect influenza. Commonly available tests are direct fluorescent antibody assays, virus culture (using Shell vials or conventional cultures), and polymerase chain reaction. As part of our increased surveillance for SOIV, clinicians may contact their local public health jurisdiction to submit a sample to the state’s Public Health Laboratory (PHL) to test for SOIV.
- For intubated patients, PHL will accept broncho-alveolar lavage or deep tracheal suction specimens if packaged and shipped properly. This is an exception to PHL’s normal policy. As a result, if the test is positive for SOIV, we will report it. But, if negative for SOIV, because this is a nonstandard sample, we must report the test as inconclusive.
- PHL will test for SOIV only and not any other respiratory pathogens
For more information about SOIV, see: http://www.cdc.gov/swineflu/ and http://www.doh.wa.gov/swineflu/default.htm
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