for National Geographic News
Poultry vaccines can prevent healthy chickens from contracting deadly strains of avian influenza, Dutch researchers report.
J. A. van der Goot and colleagues at the Central Institute for Animal Disease Control in Lelystad, the Netherlands, tested a vaccine that has been developed against the highly pathogenic H7N7 strain of bird flu.
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Vaccines are already known to help birds survive bouts of the deadly flu strain. But van der Goot's study shows that they are also effective in blocking transmission of the virus from infected birds to healthy chickens.
"People used to look at the effects of vaccine by watching birds to see if they became sick or died," she explained. "But now we have a model for looking at transmission."
The ability to curb the virus's spread between birds could become a key weapon in controlling avian flu outbreaks that might decimate flocks and increase the odds of human infections.
The group is currently testing the effectiveness of an H5-strain vaccine. Health officials warn that H5 and H7 strains of bird flu could potentially spawn a human influenza pandemic.
As yet the most deadly flu strain, H5N1, has remained an animal disease. Although about 130 people have become infected with the strain and 67 have died, H5N1 has not displayed the ability to transmit easily from person to person.
If bird flu never gains that ability, it will remain a relatively minor public health problem, experts say.
But if an H5 or H7 strain does mutate to transmit easily among humans, experts warn of a possible global pandemic that could rival the 1918 "Spanish Influenza" outbreak that killed millions around the globe.
Boosting Emergency Response
Van der Goot housed infected birds with healthy chickens to gauge the vaccine's effectiveness in blocking the spread of disease.
After two weeks the vaccine had proven effective in preventing healthy birds from contracting the flu from their sick neighbors. The findings are reported in the current edition of the Proceedings of the National Academy of Sciences.
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