Trojan Duck
Click here for a printer-friendly version of this page
Pandemics may be inevitable, but the emergence of Ebola-like superstrains may be preventable. As porous as U.S. biosecurity is, the American system offers some distinct advantages.2883 Avian influenza tests are provided free of charge by the USDA to the poultry industry, so more than a million tests have been carried out every year.2884 That’s a small percentage of the 9 billion birds slaughtered annually for human consumption in the country,2885 but is probably the best national surveillance in the world.2886 Many poultry-raising countries cannot afford to test millions of birds, and, as a result, low-path viruses can asymptomatically seed themselves undetected far and wide before additional mutations may make the disease hard to miss.2887
Confinement systems can also make the systematic culling of infected populations easier once the disease is found.2888 More and more countries are moving toward killing entire flocks infected with any H5 or H7 viruses—low-grade or not—to prevent the viruses from mutating into highly pathogenic strains, “but this is only feasible,” experts assert, “if there is financial support from local or national governments.”2889 This is another example of the industry attempting to externalize its costs by having the public subsidize its cleanup: The public bears the cost, and the risk.
With public assistance, though, countries with industrialized poultry production have historically been able to stop bird flu. In a country like the United States it may spread into a few hundred farms—even across a few states—but by killing enough birds, the virus has been stopped, whether in Pennsylvania in the 1980s or Virginia in more recent years. Costly, perhaps, but to date effective. This has led some to naïvely advocate that poultry farming worldwide be restricted to large-scale factory farms where infected birds can be “rapidly identified and culled,”2890 but industrial systems also have the opposite effect.
When a virus hits an industrial facility, it hits big. “Once high density industrial poultry areas become affected infection can explosively spread within the units,” the Food and Agriculture Organization of the United Nations writes, “and the very high quantities of virus produced may be easily carried to other units, to humans, and into the environment.”2891
The U.S. Geological Survey agrees: “Infected fowl can become virus pumps producing and shedding large quantities of infectious virus that contaminate the local environment, facilitating transmission of the virus within the population, which also increases the probability of virus spreading to sites/farms beyond the location of the original outbreak.”2892 Industrial poultry production can act as an amplifier for the virus, speeding its spread, making biosecurity next to impossible, and overwhelming tracing and culling capacities.2893 “Clearly, eradication efforts are more successful,” OIE experts have written, “if there is no massive spread into the industrial circuits of intensively reared poultry.”2894
During the 2003 H7N7 outbreak in the Netherlands, even with the Dutch Army assisting in the culling and disposal of 30 million birds, the virus still managed to slip into two other countries and expose hundreds of people to the virus, some of whom then went home and gave it to their families.2895 As the WHO points out, despite modern facilities in an industrialized country with a well-developed agricultural and veterinary infrastructure the elimination of the infection in poultry was “a complex, difficult, and costly undertaking.”2896 Still, though, the infection was eliminated.
To continue to keep the price of chicken meat as low as possible, why not move all of the world’s chickens onto factory farms and simply ramp up surveillance? Annual distribution of 45 billion or so testing kits for each bird slaughtered worldwide may seem cost-prohibitive, but may be cheaper than breeding birds with functional immune systems and raising them at a modest stocking density in a sufficiently clean, ventilated, and low-stress environment. In the hypothetical scenario in which the global flock has been effectively Tysonized, the individual intensive confinement facilities may remain potential breeding grounds for highly pathogenic strains, but the virus would presumably be caught early enough to limit its spread. With enough resources and enough killing, the industry has shown historically that any virus could be stamped out. History changed, though, with H5N1.
No one imagined that a killer influenza virus might be able to reinfect its natural hosts without killing them; no one thought a bird flu virus could have it both ways. In its natural waterfowl reservoir, influenza is a frequent flier. As a low-grade virus, it is flown around the world in the guts of migratory birds. In domestic poultry, the virus can grow deadly, but what it gains in virulence it loses in mobility. As one poultry veterinarian put it, “Dead birds don’t fly far.”2897 Any bird flu virus that grew deadly was presumed to sacrifice its power of flight, enabling industry to effectively mobilize against it. The z+ strain of H5N1 showed that the industry presumed wrong.2898
Initially wild birds were victims—not vectors—of H5N1. In 2002, H5N1 started killing off waterfowl in Hong Kong’s nature parks.2899 Thousands of bar-headed geese perished in China—up to 10% of the world’s population of the species.2900 Professor Shortridge speculated that H5N1 might be capable of “ecocide,” wrecking the ecosystem by killing off wild bird species, creating a kind of global Silent Spring.2901 But by early 2004, the virus was showing a trend of decreased pathogenicity in ducks, while remaining highly pathogenic in chickens and children.2902 Forced into land-based poultry, H5N1 turned ferocious. When it next encountered waterfowl, the virus was devastating. But H5N1 gradually acquired the worst of both worlds, retaining its ability to harmlessly infect globe-trotting waterfowl while continuing to kill poultry and people.2903
H5N1 no longer has to start from scratch. It was caught early enough once, in Hong Kong, and destroyed. Its re-emergence in 2001 is thought to have been an independent event. Once it attained the unprecedented2904 ability to jump back into waterfowl from poultry, though, it could become endemic in the world’s wild bird population.2905 This not only enables the virus to spread around the world and make it virtually impossible to eradicate, it allows for the continual ratcheting up of mutations without disruption. “We cannot contain this thing anymore,” Webster told the Los Angeles Times. “Nature is in control.”2906
Now that we know what bird flu viruses are capable of, we can no longer pretend that we can keep them locked up. They may come into a factory farm on a boot as a low-path virus, but they may escape on a boot, or in a mouse, or on a fly, as a high-path virus. During the Pennsylvania outbreak, H5N2 was found in more than 100 wild birds and rodents in the affected area.2907 No longer is just the neighboring farm at risk. Now we know that viruses with presumed pandemic potential can escape into the global ecosystem. With that in mind, we must focus on preventing the birth of these viruses in the first place.
Both Vietnam and Thailand2908 have taken steps to restrict or ban duck and goose farming, but this may be too little, too late.2909 Domesticated ducks are presumably more likely to transmit the virus to chickens, given their greater proximity and the continued existence of viral melting pots like live poultry markets and live animal transports. However, ending their domestication would not be expected to eliminate the risk entirely, given the presence of wild waterfowl overhead. Still, the two billion domesticated ducks farmed by people in East Asia are two billion more experimental hosts than we need allow these viruses.2910
The earth will be bombarded with influenza virus as long as there are wild waterfowl. The viruses almost always start out harmless, though. They only seem to grow dangerous once they hit poultry—and seem only to grow really dangerous in modern-day industrial poultry farms.