Saturday, April 18, 2009

urban chickens: solving the spread of bird flu

This is the fourth post in a series exploring some of the more common concerns I see raised in the debate to allow urban chickens. (see previous installments: salmonella fears, what to do with the poop and the cost to enforce urban chicken laws)

Today's topic is the argument I see thrown earliest and most carelessly by any naive naysayer in the discussion of legalizing urban chickens: "brilliant idea! Chickens in the yard next door. Hasn't anyone heard of bird flu?!?"

the best response to this is to take a few minutes (four, to be exact) to watch the embedded movie below to make you more educated about bird flu than 98% of the population. I'll see you once you scroll below the flick:

So, as the movie says, and as the research, some of which I share below, shows: our backyard flocks are actually part of the solution, not part of the problem of spreading bird flu throughout the world.

The Origins of Bird Flu

Dr. Michael Greger has written a wonderful book, Bird Flu -- A Virus of Our Own Hatching, that delivers a meticulously detailed, yet highly readable, examination of bird flu and what it means to us. (Those of you who've seen Mad City Chickens will recognize him from the vignette covering bird flu in the movie).

Here's his brief recap of how the flu came about and why it's coming out of Asia:
Experts think human influenza started about 4,500 years ago with the domestication of waterfowl like ducks, the original source of all influenza viruses. According to the University of Hong Kong’s Kennedy Shortridge, this “brought influenza viruses into the ‘farmyard,’ leading to the emergence of epidemics and pandemics.” Before 2500 B.C.E., likely nobody ever got the flu.

Duck farming dramatically spread and intensified over the last 500 years, beginning during the Ching Dynasty in China in 1644 A.D. Farmers moved ducks from the rivers and tributaries onto flooded rice fields to be used as an adjunct to rice farming. This led to a permanent year-round gene pool of avian influenza viruses in East Asia in close proximity to humans. The domestic duck of southern China is now considered the principal host of all influenza viruses with pandemic potential.

This is probably why the last two pandemics started in China. According to the UN Food and Agriculture Organization (FAO), China is the largest producer of chicken, duck, and goose meat for human consumption. It accounts for 70% of the world’s tonnage of duck meat and more than 90% of global goose meat. China has more than two dozen species of waterfowl. As Osterholm has said, “China represents the most incredible reassortment laboratory for influenza viruses that anyone could ever imagine.”

Extensive sampling of Asian waterfowl in the years following the Hong Kong outbreak seems to have tracked H5N1 to a farmed goose outbreak in 1996, the year the number of waterfowl raised in China exceeded 2 billion birds. The virus seemed to have been playing a game of Duck, Duck, Goose…then Chicken.
If you take a look at any of the World Health Organization (WHO) maps showing the spread of H5N1 avian influenza, you'll notice right away the Western Hemisphere is missing from the map. Why? Because the H5N1 virus has never been found in North or South America.

Since 2003, H5N1 has infected at least 411 people in 15 countries and killed 254. It has killed or forced the culling of more than 300 million birds in 61 countries in Asia, the Middle East, Africa and Europe. When you look at the Google News bird flu stories, you'll see where they're not coming from: North and South America.

Factory Farming and the Fragile Flock

In order for the flu virus to mutate, it has to have plenty of infected host bodies to use to evolve from one strain to the next as it find the best way to exploit the host body.

Factory farms, where hundreds of thousands of birds are kept in close proximity in their battery cages, are the perfect breeding ground for viruses to mutate and spread. The economics are simple: if we want cheap eggs and cheap chicken meat, the conditions must be crowded which lead to stressed birds and suppressed immune systems which further enable the virus to mutate and jump.

And it's just these kind of conditions that make it easy (and necessary) for the culling of millions of birds in a short period of time to prevent an influenza from spreading from just a few infected birds to millions. Great fodder for headlines.

When you look at our backyard flocks of six, twelve or even twenty chickens, there simply isn't a sufficient pool of bodies for the flu virus to mutate enough to make the leap from affecting the intestines of the fowl to infecting the lungs of a mammal (or human).

Moreover, the fact we're keeping our chickens in free-ranging (or close to it) environments means the flu virus is likely exposed to sunlight which quickly kills the virus and prevents it from spreading. Compare the sunlight exposure of even the most crowded narrow backyard to the cavernous dank and dark conditions inside a factory farm chicken house, and you can easily see which environment is more likely to contribute to the flu's spreading.

Dr. Gerger continues:
All bird flu viruses seem to start out harmless to both birds and people. In its natural state, the influenza virus has existed for millions of years as an innocuous, intestinal, waterborne infection of aquatic birds such as ducks. If the true home of influenza viruses is the gut of wild waterfowl, the human lung is a long way from home. How does a waterfowl’s intestinal bug end up in a human cough? Free-ranging flocks and wild birds have been blamed for the recent emergence of H5N1, but people have kept chickens in their backyards for thousands of years, and birds have been migrating for millions.

In a sense, pandemics aren’t born—they’re made. H5N1 may be a virus of our own hatching coming home to roost. According to a spokesperson for the World Health Organization, “The bottom line is that humans have to think about how they treat their animals, how they farm them, and how they market them—basically the whole relationship between the animal kingdom and the human kingdom is coming under stress.” Along with human culpability, though, comes hope. If changes in human behavior can cause new plagues, changes in human behavior may prevent them in the future.
The Mythology of Urban Chickens and Avian Flu

Everyone remembers that lone cow that kicked over the lantern in the O'Leary's barn to start the Great Chicago Fire of 1871 which killed hundreds and destroyed four square miles of buildings. Well, it turns out the cow causing the fire was a myth, created by Michael Ahern, a Chicago Republican reporter, to sell the story of the fire better.

It seems urban chickens are getting the same fanciful treatment when it comes to fear-mongering about bird flu, specifically the H5N1 virus which is regarded as poised to become the next pandemic.

What people don't seem to realize is that our urban chickens are the solution to stopping H5N1, not the problem!

I close with this last quote from Dr. Gerger's book:
To reduce the emergence of viruses like H5N1, humanity must shift toward raising poultry in smaller flocks, under less stressful, less crowded, and more hygienic conditions, with outdoor access, no use of human antivirals, and with an end to the practice of breeding for growth or unnatural egg production at the expense of immunity. This would also be expected to reduce rates of increasingly antibiotic-resistant pathogens such as Salmonella, the number-one food-borne killer in the United States. We need to move away from the industry’s fire-fighting approach to infectious disease to a more proactive preventive health approach that makes birds less susceptible—even resilient—to disease in the first place.
Sounds like a ringing endorsement of urban chickens to me. Why some cities still refuse to legalize them seems all the more insane to me now.


OneWetPig said...

Great post! We plan to make an urban chicken bylaw push in my community after the next round of municipal elections. Debunking the bird-flu concerns will be a help.

Could you address the "chickens attract rat" question in your next post? That is the other big issue people are fretting about here.

Anonymous said...

I wish your site had less of an anti-duck bias. I am in the process of defending my right to keep my pet ducks and one of the attacks against them is the risk of bird flu. They are a breed that cannot fly and the only water they are exposed to besides their drinking water is a bathtub or a kiddie pool. They stay confined in my yard. There's never been H5N1 in North or South America. They're not giving anyone bird flu.

I wouldn't quote your site, though I find it useful and informative, because of the finger-pointing of ducks in defense of chickens. Is it necessary?

Hazel Richardson said...

Thanks for this information! I have an application for backyard hens being heard in my city next week. I just heard that the provincial Egg Producers association is going to oppose the application on the grounds of disease, and particularly avian influenza. This will help me make my case against them....


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