To date, APHIS has been factual in their minimal reporting on the ascending incidence of bovine influenza-H5N1.  In contrast, a number of State Veterinarians have been far more optimistic in their official statements dampening concern over the potential of the virus to become zoonotic.

The major concern is the possible emergence of a zoonotic strain of H5N1 as noted by the World Health Organization that regards the virus as a potentially pandemic strain requiring surveillance over a range of avian and mammalian species.  At this time, there is no evidence that spontaneously altered strains of H5N1 are infectious to humans although affecting a wide range of terrestrial and marine species with evident animal-to-animal spread. Despite the recovery of H5N1 virus from a dairy-herd employee with conjunctivitis, the only previous U.S. case occurred in a worker involved in depopulation of an infected flock.  Given thousands of worker hours of exposure in 2015 and then again during the 2022-2023 epornitics, one asymptomatic case suggests that even with extreme exposure, humans are currently refractory to infection.

Although there have been over 800 documented cases of H5N1 or H7N9 influenza among humans in Asia over two decades, the attack rate is exceptionally low given the level of potential exposure since emergence of these strains in poultry.  Most of the cases involved either the elderly or the immunosuppressed. Patients in most instances presented with a history of contact with live poultry either on farms or in wet markets as with the two cases documented in South America in 2023.

Given the reality that migratory marine birds and waterfowl are susceptible to H5N1 and disseminate the virus across five continents, ultimately, mutations may occur that may result in a zoonotic strain.  The higher the concentration of susceptible birds or livestock in an area or on a farm, the greater will be the probability of either a mutation or a recombinant event. 

Accordingly, it would be advisable to consider human health as a justification to create non-susceptible commercial bird populations through immunization.  Currently, archaic and inappropriate trade restrictions in addition to the imposition of contrived trade barriers disfavor universal adoption of vaccination. The World Organization of Animal Health supports the principle of vaccination and clearly states that this modality should not be a restraint to trade providing there is adequate surveillance to detect infection in immunized flocks.  In the age of PCR, this is an achievable objective. It will be possible for regulatory authorities to introduce and manage a program of certification to confirm that export consignments are derived from flocks free of infection.

The concerns of the broiler segment of the U.S. poultry industry concerning vaccination are recognized.  When human health is considered, the potential of losing export sales pales in significance to even the slightest risk of an emerging pandemic. The cost of COVID with the attendant loss of more than one million of our fellow citizens suggests that H5N1 avian influenza is more than just a “chicken and turkey problem”.

It is now time to implement regional vaccination against HPAI in areas with a history of infection and specifically for turkey and egg-production flocks.  The associations representing the segments of the U.S. poultry industry, APHIS, USAPEEC and the Office of the U.S. Trade Representative need to coordinate and intensify their activities to accept rigorously controlled vaccination. As far as possible, issues relating to restraint in trade based on vaccination should be resolved given that HPAI is now panornitic in distribution.

A statement by a mid-west State Veterinarians that “research to date has shown that mammals appear to be dead-end hosts which means that they are unlikely to spread HPAI further” is simplistic and is devoid of substantiation by either current virology or epidemiology.  State Veterinarians are tasked with preserving the health of flocks and herds under their jurisdiction and should not be cheer-leaders for consumption of livestock products.  With respect to HPAI, there is more at risk than either loss of trade or the cost of depopulation.  Creating a solidly immune population of commercial poultry would contribute to a lower risk of facilitating a zoonotic strain of avian influenza.  The emergence of bovine influenza-H5N1 in March and outbreaks in mink and marine mammals should be a warning of the potential for an influenza pandemic reminiscent of the 1918-1919 catastrophe. Risks of mutation might be small but economic and humanitarian consequences are infinite.