In years past, swine-variant influenza has been our biggest concern, with more than 500 cases reported in humans by the CDC, most of which are linked to swine exposure or fair attendance.
While the risks are low, the CDC advises those who are at higher risk of serious flu complications (including children under 5, adults over 65, pregnant women, and those with certain chronic medical conditions), to avoid pigs and the swine barn altogether.
This year, we've a new concern, with H5N1 now detected in dairy cattle across at least 12 states. While human infections have been both rare and mostly mild, bringing together cows, poultry, goats, pigs, and other forms of livestock entails a certain amount of risk.
In their Epidemiological investigation into the spread of H5N1 in Michigan - released June 9th - APHIS/USDA cited the movement of livestock, farm equipment (including trucks), and personnel as contributing to the spread of the H5N1 virus.
All of which are part and parcel of any agricultural exhibit. In response, a number of states have released `guidance' for fair exhibitors, but these vary significantly from state to state (see here, here, here, and here), and no one really knows how much biosecurity is enough.
Some states have prohibited poultry exhibitions entirely, while others still appear to be on the schedule. Conspicuously, some states are apparently mandating enhanced livestock biosecurity, while others only appear to be `urging' farmers to take precautions.
Admittedly, many of these mandated biosecurity measures can be onerous, and very expensive - but that doesn't mean they aren't prudent. H5N1 in cows and poultry is concerning enough, but if it spreads into other livestock - particularly swine - our problems could quickly escalate.
Since cattle aren't generally hosts for influenza A, the chances of seeing a reassortment occurring in dairy cows is probably very low.
But swine are notoriously good hosts for a wide variety of influenza A viruses, and have a reputation as being an excellent `mixing vessel' for influenza.
While no one can predict what would happen if H5N1 made it into swine, this is a field experiment we really don't want to see conducted.
This was obviously a very difficult decision, but one I expect to become more common as the daunting logistics of trying to prevent the spread of H5N1 at these venues becomes more apparent.
But should H5N1 expand further into American livestock, there may be even more difficult decisions ahead.
Stay tuned.
