Recent research on ferrets confirmed aerogenous spread of H1N1 influenza virus.  The quantum of virus shed by ferrets under controlled experimental conditions is a function of transmission efficacy.  Detection of viral RNA in air indicates the potential for aerogenous transmission of H5N1 infection from wild bird reservoirs congregating in the vicinity of farms. The aerogenous route of introduction of virus onto farms has been the subject of research in Holland and Taiwan and is widely accepted by U.S. poultry health professionals based on anecdotal reports and field observations.

It is reasonable to assume that large egg production complexes may be especially vulnerable to airborne infection due the volume of air entering houses under high rates of powered  ventilation. A three-level aviary house with 300,000 hens operated at 1cfm per lb. biomass would require displacement of 1.2 million cfm. If in practice aerogenous infection is a reality, even the most effective structural and operational biosecurity cannot provide absolute protection notwithstanding “protect the flock” posters and recommendations provided by APHIS speakers at regional and national meetings.