BBC: Avian flu, who's to blame

[Guest guest]

http://news.bbc.co.uk/1/hi/sci/tech/4721598.stm

 

Reality takes wing over bird flu

 

VIEWPOINT

Leon Bennun

 

 

Vested interests mean wild birds are being

blamed for the spread of avian flu, argues Dr

Leon Bennun in this week's Green Room, whereas

responsibility really lies with modern farming.

Demands for culling and the destruction of

nesting sites threaten, he says, to bring rare

species to extinction, but will do nothing to

halt the disease.

 

The role of migratory wild birds in the

transmission of the disease has been exaggerated

and sensationalised

 

During the second week in February, Western

Europe reported its first cases of the highly

pathogenic H5N1 strain of avian flu in wild birds.

 

Across Italy, Greece and Slovenia, more than 25

mute swans died; by Valentine's Day, the virus

had also been found in wild swans in Austria and

Germany.

 

Conservationists, poultry keepers and health

officials are bracing themselves for more

widespread outbreaks.

 

Fuelled in part by alarmist press reports and by

the attempts of government agencies to draw blame

away from farming, there are now calls for

drastic measures against wild bird populations.

 

I believe these measures would put some species

at risk of extinction, without having any effect

on the spread of avian flu.

 

Catching the culprits

 

The likelihood is that the swans now dying in

Western Europe had recently arrived from the

Black Sea, driven south and west by freezing

conditions that prevented them feeding.

 

They may have caught the disease from other wild

birds; but this is unlikely given the tens of

thousands of waterfowl that have tested negative

for H5N1 over the last decade.

 

Much more likely is that before starting out,

they picked up the virus from farms, either from

infected poultry or their faeces. Mute swans

often graze agricultural fields, and are likely

to have come into contact with poultry manure

spread as a fertiliser.

 

If wild birds had been spreading the disease

across continents there would have been trails of

outbreaks following migration routes; but this

hasn't happened.

 

The " wild bird " theory for the spread of H5N1

also provides no explanation as to why certain

countries on flight paths of birds from Asia

remain flu-free, whilst their neighbours suffer

repeated infections.

 

What is striking is that countries like Japan

and South Korea, which imposed strict controls on

the import and movement of domestic poultry after

initial outbreaks, have suffered no further

infections. Myanmar has never had an outbreak.

 

In fact, countries which have not yet developed

a large-scale intensive poultry industry have

also been largely spared. The UN Food and

Agriculture Organization (FAO) reports that in

Laos, 42 out of 45 outbreaks affected intensive

poultry units.

 

Lethal evolution

 

Highly pathogenic avian influenza viruses are very rare in wild birds.

 

Intensively-farmed poultry provide ideal

conditions for the evolution of highly lethal

forms

But in intensively farmed poultry, the high

density of birds and constant exposure to faeces,

saliva and other secretions provide ideal

conditions for the replication, mutation,

recombination and selection through which highly

lethal forms can evolve.

 

Add to this repeated misdiagnosis, industry and

government cover-ups, and panic selling or

processing of potentially infected birds, and we

have the explanation for why H5N1 is now endemic

in parts of South-East Asia.

 

Factor in the global nature of the poultry

industry, and the international movement of live

poultry and poultry products both before and

after the Asian outbreaks, and we have the most

plausible mechanism for the spread of the virus

between places which are not connected by the

flyways of migratory birds.

 

The timing and pattern of outbreaks has been

largely inconsistent with wild bird movements;

but they have often followed major trade routes.

 

The view that poultry movements have played a

major role in the spread of the disease is

supported by an analysis of viral strains

recently published in the US journal Proceedings

of the National Academy of Sciences.

 

Some of the agencies attempting to monitor and

control avian flu, such as the FAO, seem to have

been reluctant to draw attention to the role of

intensive agriculture, because of the impact on

national economies and on access to cheap sources

of protein.

 

Senseless destruction

 

For this and other reasons, the role of

migratory wild birds in the transmission of the

disease has been exaggerated, and further

sensationalised in the press.

 

In some countries there has been a backlash

against bird conservation, leading to calls for

the culling of whole populations, draining of

wetlands and destruction of nesting sites.

 

In fact, H5N1 outbreaks in wild birds have so

far mostly burned themselves out without culls or

other human interventions.

 

Some of the world's most threatened birds may be

put at risk. But there is also the near-certainty

of damage to ecosystem services on which people

and economies depend.

 

Alarmingly for those who fear a human bird flu

epidemic, such a distorted picture also means

that the right questions are not being asked, and

the most effective protection measures may not be

undertaken.

 

BirdLife is calling for an independent inquiry

into the spread of H5N1 which gives due weight to

the role of the global poultry industry, and maps

both official and unofficial poultry trade routes

against the pattern of outbreaks.

 

It may also be time to take a long, hard look at

the way the world feeds itself, and to decide

whether the price paid for modern farming in

terms of risks to human health and the Earth's

biodiversity is too high.

 

Dr Leon Bennun is Director of Science, Policy

and Information for BirdLife International.

 

The Green Room is a series of opinion articles

on environmental issues running weekly on the BBC

News website

 

A series of thought-provoking environmental opinion pieces

Story from BBC NEWS:

http://news.bbc.co.uk/go/pr/fr/-/1/hi/sci/tech/4721598.stm

 

Published: 2006/02/17 09:56:46 GMT

 

© BBC MMVI

 

--