Credit: Terry J. Alcorn
Everyone's getting all worked up about avian flu. Will the virus spread to North America? Will it mutate and spread between humans? Will it Kill Us AllTM? Valid questions, to be sure, and these concerns have led several nations to decimate bird populations in an effort to stop H5N1 in its tracks.
Romania recently culled 1 million domestic birds; India deep-sixed between 300,000 and 500,000; and Germany took out 400,000 of its poultry stock. In Iran, Slovenia and the UK, the most elegant of birds, the swan, has been slaughtered in the name of public safety when a couple of its ilk were felled by avian flu. In Thailand, sparrows succumbed to the paranoia of a pandemic.
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It is truly a shame to lose our fine, feathered friends. Sparrows are adorable chirpers, swans radiate enough grace to inspire balletic masterpieces and chickens go really well with a nice sweet and sour sauce. But, in these avian dark ages there's a glimmer of light.
Recently, New York state pathologist Ward Stone told the New York Post that the city's 100,000 pigeons could all be euthanized should bird flu make it to the area.
Pigeons are perhaps the vilest scum to waddle above ground. They congregate in public squares, barely clear the top of your head when you invade their personal space and yet achieve remarkable accuracy when aiming their poop.
Unfortunately, it's likely the extinction of the pigeon wouldn't do anything for public health, and if the authorities catch on, we may not experience the joy of a mass execution. According to experts, there's nary a bird more robust than the pigeon when it comes to bird flu.
"Generally, you can't even infect pigeons, even with high doses [of the flu]," said David Swayne, director of the USDA's Southeast Poultry Research Laboratory. "If you give them high doses, occasionally you can get infected pigeons, but they usually don't shed very much virus."
Swayne has made it his business to shoot obscenely large doses of avian flu into pigeons' noses, using three strains of H5N1 in his experiments: The first, a strain found in Hong Kong in 1997, failed to infect even one pigeon, even when he gave them a far higher dose than they would ever encounter in nature. His other two strains were both found in birds isolated in Thailand in 2004, one a dead pigeon, the other, a dead crow. He nasally administered a high dose of the Thai strains to six pigeons each. Only one of these birds died. Six showed signs of infection but never became sick, and Swayne couldn't even detect the virus in the other five.
"I guess the bottom line is pigeons do not host influenza well at all," said Paul Miller, an avian diagnostician at the Pennsylvania Veterinary Laboratory. "The more pathogenic strains, they will be able to host, but it's not normally thought of as a pigeon disease."
While the virus in its current state won't drive pigeons into the annals of history, it's always possible the right mix of mutation and recombination will produce a virus so finely tuned to pigeons that our picnic food will never be touched by their dirty beaks again.
Miller explained that we humans are resistant to H5N1 because the receptors that bind the virus lie deep in our respiratory system. In order for the virus to penetrate far enough to reach those receptors, we need to be exposed to a very high load. Other airborne viruses bond with different, more accessible receptors in our upper respiratory systems, so we contract those illnesses much more easily.