Chickens stand in their cages at a farm near Stuart, Iowa. Discovery of bird flu on an Iowa turkey farm has raised serious concerns that the bird killer could find its way into chicken barns and rapidly decimate flocks.
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Photograph by Charlie Neibergall, AP
Chickens stand in their cages at a farm near Stuart, Iowa. Discovery of bird flu on an Iowa turkey farm has raised serious concerns that the bird killer could find its way into chicken barns and rapidly decimate flocks.

The Avian Flu Epidemic: Massive Impact, Uncertain Future

You might have to be an avid reader of medical journals—or a poultry farmer—to notice that the United States is in the midst of a slow-motion disease disaster.

The disease is avian influenza, and though it has not, as yet, affected any people, it is wreaking havoc nonetheless. As of Monday, almost 26 million chickens and turkeys have either died, or been killed to keep the disease from spreading. Three states—Iowa, Minnesota and Wisconsin—have declared states of emergency. Layoffs have begun at poultry farms, and the industry is warning that there may not be enough surviving turkeys to  fill tables at Thanksgiving. The federal government has released $330 million in emergency funds, and in Minnesota, the National Guard has been called out.

Twenty-six million sounds like a lot of birds—but while the epidemic is devastating to states and to individual farmers, so far it has barely dented the United States’ poultry supply. The U.S., after all, produces about 9 billion meat chickens, 360 million laying hens and 240 million turkeys per year; the current losses equal less than three-tenths of one percent of the total.

Poultry raising, though, is an intricate economy of many moving parts. The potential losses from this epidemic include not only individual farm businesses—that is, the income of farm families, and of their workers and their families—but also the businesses they use, from feed dealers to equipment sales and service to slaughterhouse and packing workers to the cafe in the local town.

Beyond that, there is an international ripple effect as well. Each of the top 10 importers of U.S. poultry products has either banned their being imported or restricted them in some way. Those restrictions extend beyond meat and eggs to breeding stock—which means that, if the epidemic continues, other countries will see cuts in their poultry supply too.

And even more than the economic impact, there is concern about a possible medical one. A particular strain of avian influenza—technically, high-pathogenic H5N1—caused great alarm in 1997. (See my last post on bird flu for a short primer on terminology.) It jumped from birds to humans in Hong Kong, sickening 18 people and killing six of them. It was suppressed only by killing all the chickens in the Hong Kong territory—but flared up again in 2003 in Vietnam, and began moving through Asia and west. To date, according to the World Health Organization, it has sickened 826 people and killed 440, more than half of them.

And because the greatest flu pandemic known to history, the “Spanish flu” of 1918—which killed at least 50 million and possibly 100 million people around the world— began as an avian virus, disease authorities watch any bloom of bird flu carefully, braced in case another strain makes that bird-to-human leap.

There is no evidence yet that this bird flu has. “While we are cautiously optimistic that there will not be human cases, we must be prepared for that possibility and we are taking routine preparedness steps, including studying these viruses further and creating candidate vaccine viruses which could be used to make a vaccine for people if one were needed,” Dr. Alicia Fry of the Centers for Disease Control and Prevention said on a CDC-USDA conference call two weeks ago. “So far, genetic analysis has not shown any of the markers that are known to be associated with increased severity of illness in people or an increased ability to be spread to people or spread among people.”

A remarkable thing about this epidemic: It has been spreading since last December (as I covered at our sister blog The Plate).It was spotted first in British Columbia, hopped cross-border to Washington and Oregon, and then began to move inward across the continent. It exploded when it reached Minnesota, the center of the turkey industry, and Iowa, one of the centers of the egg industry, because the farms where the virus has landed are enormous: One chicken facility held 5.7 million birds, two others held more than 3 million, and the two largest turkey farms housed more than 300,000 each.

I spoke to several scientists working on the outbreak who asked not to be identified. They acknowledged that exactly how this flu is spreading is not clear. The usual source of avian flu is wild waterfowl, primarily ducks, which pick the strains up in Asia without being made sick by them, and spread them across the globe as they migrate. Ducks can intermingle with backyard poultry—and they were observed doing that in the British Columbia outbreaks, which occurred on small farms—but they have little chance of making contact with conventionally raised birds. Those large farms (such as the multi-million-bird ones in this outbreak) keep their birds entirely inside buildings, and are expected to have tight biosecurity precisely because confined conditions make it easier for diseases to spread.

The scientists I spoke to said it is possible the flu is now being spread, not by other birds, but by humans—and not because the humans are infected, but because they are unknowingly transporting the virus from one place to another. That could happen via anything that comes onto a farm and has already been on another farm: a truck, car tires, even the clothing or equipment of delivery drivers, equipment-service workers or veterinary technicians. It could even come from water sources elsewhere on a farm that have been contaminated by ducks landing on them, if the water is used to spray down barns or flush away manure.

If that speculation is correct, then controlling the spread of the virus will be unusually challenging—but it will have to be managed, because biosecurity is the industry’s current best defense. Unlike some other countries, the United States does not routinely vaccinate poultry against bird flu. One researcher I spoke to described an outbreak of this size as being like a 100-year flood: for 99 of those years, the expense of vaccinating flocks would not be justified, and—unless it was mandatory for all producers—could put some farmers at a competitive disadvantage versus other farmers who did not buy the vaccine.

(In fact, the last major outbreak of high-pathogenic bird flu in the U.S. was not 100 years ago, but 32: There was a multi-state outbreak in 1983-84, when 17 million birds died or were killed. Before that, the last large U.S. outbreak was in 1929.)

I asked the sources who talked to me what they expected to happen next, and they were cautious. Influenza viruses prefer cooler weather; in the USDA’s April briefing, officials predicted viral spread would slow as summer arrives. That would solve the problem, but only until autumn, when migrating waterfowl could bring the virus south again. If high-pathogenic bird flu became something that had to be defended against every year, that could force  the poultry industry to change its operations in significant and expensive ways.

What the risk is of that happening, no one yet can say.