The reported symptoms of humans with
bird flu have ranged from typical
influenza-like symptoms (fever, cough, sore throat, and muscle aches) to eye infections (conjunctivitis), pneumonia, acute respiratory distress, viral pneumonia, and other severe and life-threatening complications.
Four different influenza
antiviral drugs (
amantadine,
rimantadine,
oseltamivir, and
zanamivir) are approved by the U.S. Food and Drug Administration (FDA) for the treatment of influenza; three are approved for prevention. All four drugs have activity against influenza A viruses. However, sometimes, influenza strains can become resistant to these drugs, and, therefore, the drugs may not always be effective. For example, analyses of some of the 2004
H5N1 viruses isolated from poultry and humans in Asia have shown that the viruses are resistant to two of the medications (amantadine and rimantadine). Monitoring of
avian influenza A viruses for resistance to influenza antiviral medications is ongoing.