BBC Avian flu moves among wild geese

[Guest guest]

>BBC DAILY E-MAIL: UK EDITION

>Thursday, 07 July, 2005, 8:00 GMT 01:00 -07:00:US/Pacific

>

> * Avian flu moves among wild geese *

>An outbreak of avian flu in wild geese in China

>raises fears that the virus reponsible could

>soon spread beyond its Asian stronghold.

>Full story:

>http://news.bbc.co.uk/go/em/-/1/hi/sci/tech/4657145.stm

>

Avian flu moves among wild geese

An outbreak of avian flu in wild geese in

western China has raised fears that the virus

responsible could soon spread beyond its Asian

stronghold.

 

Researchers say evidence of the H5N1 pathogen in

the geese is a big concern because of the

migratory animals' ability to fly huge distances.

 

Their reports, in the Science and Nature

journals, are the first to show viral

transmission between wild birds.

 

Previously, the flu was only seen to move to wild birds from domestic fowl.

 

World health officials are worried avian

influenza virus (AVI) could cause a pandemic of

human disease if it ever acquires the ability to

pass easily from human to human.

 

H5N1 BIRD FLU VIRUS

Principally an avian disease, first seen in humans in Hong Kong, 1997

Almost all human cases thought to be contracted from birds

Isolated cases of human-to-human transmission in

Hong Kong and Vietnam, but none confirmed

So far, the impact on people has been limited to

54 deaths out of 154 infections in Vietnam,

Thailand and Cambodia - again, after contact with

domesticated chickens and other infected food

birds.

 

News that the H5N1 viral strain is now being

passed around wild geese makes avian flu even

more of a global threat than it already is, the

scientists say.

 

" These birds can fly one thousand miles a day at

maximum, " explained Yi Guan, of the University of

Hong Kong, China.

 

" This means the virus has the opportunity to

expand its distribution to currently virus-free

areas, " he told BBC News.

 

Global threat

 

The reported outbreak was first detected on 30

April in bar-headed geese ( Anser indicus ) at

Lake Qinghai, a protected nature reserve in

Qinghai Province.

 

The animals displayed classic symptoms, such as

tremors, diarrhoea, head tilt and paralysis.

 

By 20 May, the outbreak had claimed some 1,500

birds, report Yi Guan and colleagues in Nature;

not just bar-headed geese, but great black-headed

gulls ( Larus ichthyaetus ) and brown-headed

gulls ( Larus brunnicephalus ).

 

Genetic analysis of the virus extracted from

dead birds shows that it is closely related to

the strain that has caused human illness in

Thailand and Vietnam.

 

Lake Qinghai is a major breeding centre for

migrant birds, say to Jinhua Liu and colleagues

in Science magazine. Bar-headed geese are known

to move south to Burma and north over the

Himalayas to India.

 

In their report, Liu's team analysed a variety

of birds collected from the lake. The scientists

managed to isolate four H5N1 virus sub-strains,

and tests on mice and chickens showed them to be

highly virulent.

 

Fifteen of the 16 test animals were dead within three days of exposure.

 

" The occurrence of highly pathogenic H5N1 AIV

infection in migrant waterfowl indicates that

this virus has the potential to be a global

threat, " Liu's team write in Science.

 

Evidence of spread in wild geese means farmers

outside of southeast Asia should now be more

vigilant for signs of the disease, the research

teams say. Avian flu is almost impossible to

stamp out once it becomes established in farm

poultry populations, they warn.

 

Story from BBC NEWS:

http://news.bbc.co.uk/go/pr/fr/-/1/hi/sci/tech/4657145.stm

 

Published: 2005/07/07 06:27:00 GMT

 

© BBC MMV

 

--