Does Killing Birds Help Stop Spread of Bird Flu?

March 28, 2006 — -- The rapid worldwide spread of the deadly H5N1 virus -- more commonly known as bird flu -- has caused concern among scientists and emergency response experts all over the world.

"There is a real threat, and I think the situation we are facing today is quite alarming," said Albert Osterhaus, a veterinary scientist and virologist at the Erasmus Medical Center in the Dutch city of Rotterdam. "We really fear that this particular virus might be at the basis of the first pandemic outbreak of influenza in the 21st century."

Health officials in the United States suggest that bird flu is likely to arrive in North America this year; it will be carried by wild birds migrating thousands of miles to their summer breeding grounds, and flu bird experts have warned us to prepare for the worse.

To help quell the outbreak, health officials across the world have ordered the mandatory culling of domestic birds either infected or at risk of becoming infected. But some doubts have been raised about the effectiveness of this practice.

After an outbreak in birds earlier this year, European countries opted initially for the immediate culling of poultry in endangered areas. France and the Netherlands had tens of thousands of chickens and geese killed as they worked to keep the virus under control.

And Israel -- located at a crossroads of migrating flocks on their way to breeding grounds -- killed some 400,000 to 500,000 domestic birds after the first infected wild avians were found there.

But as the virus spreads, hope is fading that this strategy will work; authorities have been forced to rethink such strategies as culling and vaccinations, and other efforts to fight the disease.

"It's not either-or. It's not culling versus vaccination. It's not if culling does not work, we'll vaccinate the birds," Osterhaus said. "Both culling the birds and vaccinating the birds are legitimate tools to be used according to the individual local requirements. And one does not work without the other."

European Union officials have approved plans by France and the Netherlands, the EU's two largest poultry producers, to carry out preventive vaccination on millions of birds against the H5N1 strain of the bird-flu virus.

The vaccine is effective in birds, but a potential vaccine for humans is still being tested. The anti-viral medication, Tamiflu, is regarded as the best currently available treatment for bird flu in humans.

Officials argued that recent outbreaks of bird flu intensified the need to explore every possible option to fight its spread, "and that includes preventive vaccination, accompanied by sufficient guarantees of tight surveillance," said EU Health Commissioner Markos Kyprianou.

Vaccination will be allowed in the Netherlands for free-range poultry, since those are most in danger of contact with wild birds, as an alternative to keeping them indoors.

France can vaccinate ducks and geese in three areas in the west and southwest thought to be at high risk.

Russia also approved a massive vaccination program after officials admitted they couldn't contain the virus, now that some 800,000 birds have been culled.

In England leading animal health experts insist that bird-flu vaccine is no "silver bullet" and a government spokesman said that at present vaccines were "not a path that they would want to go down. Vaccination of poultry offers potential benefits, but currently available vaccines are too limited to provide a general solution."

Several European countries initially opposed the EU's move to allow vaccination of poultry, as health experts feared it could lead to the evolution of new strains, increasing the risk of a human pandemic.

Health officials were also quick to point out that only intensive surveillance could stop this from happening, and vaccines, especially flu vaccines, are not 100 percent effective.

While vaccines can prevent animals from becoming ill, a low number of viruses can still replicate inside their bodies and spread from animal to animal. Such "silent epidemics," as they are called, are very hard to spot but can cause new outbreaks if unvaccinated animals are exposed.

Veterinary scientists usually prefer to control livestock epidemics by destroying sick and exposed animals, instead of vaccinating them. But with avian flu affecting huge areas of Asia, there are fewer choices now. Vaccination could help end the outbreaks more quickly. Fewer flocks destroyed would leave fewer small-scale poultry farmers destitute, sources said.

"Vietnam is a good example where vaccinating the birds has worked quite well," said Juan Lubroth, a senior officer and expert on infectious animal diseases at the U.N.'s Food and Agriculture Organization in Rome. "After about a year and a half of culling the chickens and geese, Vietnam still had not been able to eradicate the disease and began to vaccinate the flocks. Since December of last year, no outbreaks have been reported post-vaccination, which means there's a positive result," said Lubroth.

"Then, of course, there's also the important component of compensation, when hundreds of thousands of poultry are killed. If you do not compensate those poultry farmers, you pull the carpet from under their feet," Lubroth continued. "The compensation factor kicks in and makes people opt for culling those birds in the immediate danger zone, and preventively vaccinate those not immediately threatened."

In Europe, where poultry sales have plunged significantly since the confirmation of H5N1 outbreaks, authorities have discussed the economic impact on the poultry industry and how to compensate the poultry farmers.