USDA -APHIS has confirmed H5N1 avian influenza in a non-commercial flock in Honolulu County, Hawaii. This is the first diagnosis in the state during the ongoing HPAI epornitic that commenced in the ‘Lower 48’ in 2022. At the time of publication a second case has been recognized
In the absence of reports on sequencing of the H5 isolate the source is a matter of speculation. Migratory marine birds may have introduced infection since Hawaii falls within the Pacific flyway. Alternatively the virus could have been carried to the state by fomites or following illegal clandestine movement of game fowl from the U.S. mainland, Guam or other areas.
A concerning observation is a report of isolation of H5 RNA in wastewater sampled from Oahu on November 7th. The isolate is currently undergoing characterization to determine whether it is an H5N1 strain.
Hawaii would be a suitable test location to evaluate the benefit of vaccination since the state does not export poultry. The County of Honolulu includes a number of commercial egg production farms that could be protected. By selective vaccination outbreaks of HPAI in the County of Honolulu could be compared to the incidence in backyard flocks and the feral chicken population of other islands over coming months. This could confirm the benefit of vaccination.