The hunt for the elusive cause of the avian influenza outbreak at
Central Poultry Development Organisation & Training Institute
(CPDOTI) on Tuesday saw officials of animal husbandry department blaming
migratory birds for carrying the virus. But ornithologists have
debunked the theory despite animal husbandry officials stating that the
Hesaraghatta Lake close to CPDOTI facility which attracts migratory
birds was the culprit for the outbreak.
MB Krishna, ornithologist and ecologist reasoned that migratory birds
that have to fly thousands of kilometres to reach their destinations
could not possiblybe able to do so if they were infected. “Basically
sick birds can’t fly the kind of distances which migration requires.
These birds never weigh more than few kilograms; so how can they even
fly across India?”
Besides, he said Hesaraghatta Lake has been dry
for two years now. “So how are these migratory birds going there when
there is no water?” he said.
Ornithologist, Harish Bhat, too,
agreed with Krishna. He said the number of migratory birds had declined
in the last five-six years.
He said Karnataka receives about five to
six species of ducks from North America and Europe; Bangalore gets
about four to five species of smaller birds such as warblers from
Siberia. Then there are a few species of raptors like eagles and
harriers from Europe. They come during the winter and leave before
summer begins.
“(But) In the last five-six years, the number of
birds coming to the lakes in Bangalore have greatly reduced. Now we get
about three-four thousand birds during this season. But these birds are
not carriers. It has been wrongly understood that they do, but the fact
is such birds hardly interact with poultry as they are water- based
birds. So how can they spread this disease?” he said.
Dr
Sudheendra Rao NR, Research Fellow, National Brain Research Centre,
Manesar, Gurgaon, who has treated influenza patients and closely
connected with avian influenza-related research, said migratory birds
being blamed for the outbreak should be taken with a touch of salt.
“If
you look at the outbreaks across the world, you will see that majority
of the cases clustered around poultry. It is true that some migratory
birds (e.g Bar-headed geese) have been implicated in bringing in low
pathogenic avian influenza virus to the mainlands. But we have to
acknowledge that it actually is the local environment that is supporting
its spread. Hence, I am not sure we can blame the migratory birds
entirely for these outbreaks,” he said.
Ornithologist-ecologist
Krishna said several vets he had interacted with in the wake of the
outbreak had reportedly said that it was the hygiene factor within
CPDOTI which had caused the virus to infect the birds by lowering their
immunity systems.
“The cages in which chickens are kept in have to be properly sterilised,” he said.
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