Sentinels or Sitting Ducks?
The federal government just announced its strategic, five-point plan to detect the invasion of H5N1 avian influenza on American soil, first and foremost our westernmost regions of Alaska, the Pacific Flyway, and Pacific Islands.Â The multi-pronged surveillance for early detection of the virus in migratory birds (the USDA is supposed to identify and monitor domestic poultry operations) will unfold as follows:
- Investigation of morbidity/mortality in wild birds:Â systematic investigation of significant numbers of sick or dead birds;
- The monitoring of live, apparently healthy wild birds:Â sampling live-captured, apparently healthy wild birds to detect the presence of highly pathogenic H5N1 virus.Â Federal agencies and their cooperators plan to collect 75,000 to 100,000 samples from live and dead wild birds in 2006;
- The monitoring of hunter-killed birds: sampling waterfowl (but apparently not game birds) at hunter check stations operated by the FWS and state natural resource agencies;
- Use of sentinel animals:Â backyard poultry flocks and stationary duck flocks; and
- Environmental sampling of water and bird feces:Â federal agencies plan to collect 50,000 samples from high-risk waterfowl habitats across the United States in 2006.
This interagency plan seems reasonable on its face, assuming one sees the spread of H5N1 by migratory birds from Asia as a dire threat requiring a response of this magnitude.Â My concerns with points 1 & 2 hinge mainly on what ratio of live to dead birds the government is looking to collect up to 100,000 samples of.Â My hope is that the netting and sampling will be done by experts.Â My fear is that the identification of sick birds will not, which may lead to mass hysteria and slaughter.
Point 5 is innocuous enough.Â Point 3 also seems fair, as long as the initiative does not somehow alter hunting seasons and patterns to expose more birds to the predations of hunters.
The one facet of this master plan that raised my eyebrow was the deployment of sentinel animals.Â I understand that poultry are rather easy to press into service; they’re not going anywhere and already live for our pleasure. But how does one deputize ducks? Just clip its wings, stick it in a lake, and wait to see if it gets sick. Daniel Engber explains on Slate:
To establish a sentinel flock, you first need to build a pen or fenced-in enclosure big enough to house between 10 and 20 birds. Then you fill the enclosure with influenza-free ducks that have been raised in captivity. Each duck is tagged with an aluminum ID band, and its wings are clipped so it can’t escape the enclosure.
Once one gets past the objection of domesticating ducks in the first place (a concern I know most readers don’t share) this plan doesn’t seem half-bad.Â First, the sentinel flocks get to spend time out in the fresh air, in marshland and wetland areas where their wild waterfowl peers congregate.Â Yes, these will be places where the bird flu has already been identified over the years, but service to one’s country is not without risk. Second, this strategy is cheaper and easier to implement. Penned birds can be sampled more readily that free ones; they’ll be less disturbed by the human contact too. Last but not least, under this method, no other birds have to die, unless, that is, H5N1 actually does hit in a big way. In that eventuality, however, we’ll have much bigger concerns…