Avian Influenza Workup

Updated: Nov 17, 2015
  • Author: Nicholas John Bennett, MBBCh, PhD, MA(Cantab), FAAP; Chief Editor: Michael Stuart Bronze, MD  more...
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Workup

Laboratory Studies

If avian influenza is suspected, the laboratory should be called ahead of time and forewarned before specimens for identification of viral infection (eg, nasal washes) are obtained. Pneumatic tubing is not recommended for transport; hand transport using a leak-proof specimen bag is preferred. The specimen should be clearly labeled as "suspected AI," and the person who transports the specimen should use appropriate protective equipment.

Many laboratories are not equipped to deal with the isolation needed to safely contain avian influenza (category 3+ containment, higher than that used for HIV). If a sample is sent, the laboratory may need to be shut down for decontamination. Samples from patients with suspected avian influenza should be sent to a dedicated central reference laboratory such as at the Center for Disease Control and Prevention (CDC). The CDC laboratory can perform antiviral sensitivity testing, as well as subtyping of the virus.

Laboratory tests and findings include the following:

  • Nasal wash specimens for detection of virus and viral subtyping are crucial.
  • Leukopenia may be present.
  • Relative lymphopenia may be present.
  • Thrombocytopenia is common.
  • Elevated levels of liver enzymes (SGOT/SGPT) are common.
  • Disseminated intravascular coagulation (DIC) is rare.

Other tests, including blood cultures, lumbar punctures for CSF analysis (including polymerase chain reaction [PCR]), and sputum cultures, should be performed based on clinical suspicion for alternative or complicating diagnoses.

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Imaging Studies

Chest radiography should be performed. The most common finding is multifocal consolidation; effusions and lymphadenopathy are also observed, as well as cystic changes.

The severity of radiologically apparent disease is a good predictor of mortality, including findings consistent with acute respiratory distress syndrome (ARDS), such as a diffuse, bilateral ground-glass appearance.

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Procedures

Intubation may be necessary for ventilatory support

Lumbar punctures for CSF analysis may need to be performed based on clinical suspicion.

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