BBC 3/25/04: vaccination of chickens against avian flu in Asia could lead to new strains which are a greater danger to humans

[Guest guest]

>

>BBC DAILY E-MAIL: UK EDITION

>Thursday, 25 March, 2004, 9:00 GMT 01:00 -08:00:US/Pacific

>

> * Warning on avian flu vaccination *

>The vaccination of chickens against avian flu in

>Asia could lead to new strains which are a

>greater danger to humans.

>Full story:

>http://news.bbc.co.uk/go/em/-/1/hi/health/3564891.stm

>

 

 

The vaccination of chickens against avian flu

could lead to new strains which are a greater

danger to humans.

 

China and Indonesia are among countries

vaccinating millions of birds against the virus.

 

But experts have said the flu virus may now

mutate in vaccinated chickens into a form that

could spread from person to person, New Scientist

magazine reports.

 

The World Health Organization (WHO) said

vaccination remained one important way of

fighting the flu outbreak.

 

By mid-March, the WHO had reported 12 confirmed

cases in Thailand alone, eight of them fatal.

 

The current form of H5N1 bird flu can spread from

birds to humans, but not from person to person.

 

But scientists warned the virus is probably still

circulating among vaccinated birds and could

evolve into a form which can spread by human to

human contact.

 

This is because flu vaccines are not 100%

effective and some viruses can replicate in

animals' or birds' bodies and continue to spread

in " silent epidemics " .

 

Ilaria Capua, of the World Organisation for

Animal Health, and Richard Webby at St Jude

Children's Research Hospital in Memphis,

Tennessee, told New Scientist that without close

surveillance vaccinations run the danger of

spreading a virus.

 

Mexico

 

A study by the US Department of Agriculture's

poultry research lab in Georgia, to be published

in the Journal of Virology, found evidence that

following an outbreak in Mexico in 1995 of

another form of flu, H5N2, different strains

developed in vaccinated chickens.

 

These new forms are increasingly different to the

vaccine strain, meaning affected birds will

spread the infection more readily.

 

It is usually seen as preferable to slaughter

affected birds and animals than vaccinate.

 

A WHO spokesman backed the current policy for

tackling avian flu. He said: " Our goal is to

reduce the threat to human health. The primary

means of doing that is culling all infected

birds, but vaccination does have a role to play. "

 

Mutating

 

He said the danger of the virus mutating to a

form which could pass from human to human as a

result of vaccination was a " theoretical " one and

said this risk had to be weighed against the

danger currently posed to humans.

 

Dr Maria Zambon, of the Health Protection Agency,

said: " Drastic measures are required to reduce

avian influenza in poultry, which should in turn

reduce the risk of transmission of avian

influenza to humans.

 

" Control measures may include culling poultry

flocks, improving hygiene and vaccination. The

economic impact of repeated culling may be

disastrous and other measures need to be

considered seriously.

 

" Vaccination is one such approach which has

proven to be useful in other countries and it is

likely that it will help to reduce the burden of

disease in poultry in south-east Asia. The

success of any vaccination campaign will depend

on the proportion of chickens vaccinated. "

 

Story from BBC NEWS:

http://news.bbc.co.uk/go/pr/fr/-/1/hi/health/3564891.stm

 

Published: 2004/03/25 00:02:37 GMT

 

© BBC MMIV

 

 

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