To date, there have been 53 confirmed human cases of H5N1 avian influenza in seven states according to the U.S. Centers for Disease Control and Prevention.  Half the cases were attributed to exposure to infected dairy herds in California with 385 cases confirmed.  The remainder involved workers depopulating flocks infected with HPAI in Colorado, Washington State, Michigan and Oregon.  All the poultry and bovine-acquired cases were characterized by conjunctivitis and in some cases mild transitory upper respiratory symptoms.

The California Department of Public Health is investigating a sporadic case in a child demonstrating mild upper respiratory involvement.  The case responded to antiviral and supportive therapy, unlike the case in British Colombia where the patient is receiving  intensive care.

Public health authorities in numerous states recommend seasonal influenza vaccination for all personnel coming into contact with live poultry in order to avert a possible recombinant event. This may be possible between H5N1 avian influenza virus in a flock and a human strain that may result in a new zoonotic virus that may develop the capability for contagion subject to further mutations.