Author |
Topic: The Economist: The aves, and ave nots 《經濟學人》禽流感文章 (Read 945 times) |
|
Carrie Ma
BBS Member
BBS God
Gender: 
Posts: 390
|
 |
The Economist: The aves, and ave nots 《經濟學人》禽流感文章
« on: Mar 6th, 2006, 3:36pm » |
 Quote  Modify
|
Source: http://www.economist.com/science/displayStory.cfm?story_id=5545392
The aves, and ave nots
Feb 23rd 2006
From The Economist print edition
Avian influenza is spreading to many new countries. But migrating wild birds may not be the only culprits
IN AROUND a month, bird flu has appeared in a seemingly alarming number of new countries. The disease is already endemic in the poultry flocks of much of Asia. In the face of the relentless march of the H5N1 virus around the world, fatalism is not an appropriate response. Better to look at exactly what is going on.
The arrival of bird flu in Europe and its neighbourhood has caused most of the flap, yet the cases in Azerbaijan, Bulgaria, Greece, Italy, Slovenia, Iran, Austria, Germany, France, Hungary and Croatia are only in wild birds. In Nigeria, Egypt and India, the virus has been discovered to be widely distributed across poultry flocks.
While the presence of the virus in any form is a concern, Nigeria, Egypt and India face bigger problems coping with dense farmed avian populations, and they are less well equipped to deal with them. More significantly, it is increasingly apparent that the real and most immediate issue is to what extent wild birds, or humans themselves, are responsible for the infection's spread in poultry.
A research paper in Proceedings of the National Academy of Sciences, published online on February 10th, shows that the H5N1 virus has persisted in its birthplace, southern China, for almost ten years and has been introduced into Vietnam on at least three occasions, and to Indonesia. The authors suggest that such transmissions are perpetuated mainly by the movement of poultry and poultry products, rather than by migrating birds.
This is significant because it strongly supports bird conservationists, who have been arguing that most outbreaks in South-East Asia can be linked to movements of poultry and poultry products, or infected material from poultry farms, such as mud on vehicles or people's shoes. Conservationists also argue that live animal markets have played an important role in the H5N1's spread. Such markets were the source of the first known outbreak in Hong Kong in 1997 when 20% of the chickens in live poultry markets were infected.
BirdLife International, a conservation group, reckons there are three likely transmission routes for H5N1: commercial trade and the movement of poultry; trade in wild birds; and the use of infected poultry manure as agricultural fertiliser. Bird conservationists add that although migratory birds can carry and transmit the virus, it is often not clear whether they picked up the infection from poultry.
In Nigeria, there is the suggestion that it was trade, and not migratory birds, that caused the outbreak. For one thing, the infection was first detected in a commercial farm with 46,000 poultry and not among backyard flocks which represent 60% of the country's poultry production—and which would be expected to have greater contact with wild birds.
The United Nations Food and Agriculture Organisation (FAO) estimates Nigeria imports around 1.2m day-old chicks every year. Further, there are rumours that many of these chicks are still arriving from countries with domestic H5N1 infections, such as China and Turkey. Joseph Domenech, head of the animal health service at the FAO's headquarters in Rome, says the importation of chickens from contaminated countries is forbidden.
The Nigerian government is now taking action to eliminate the virus. Its challenge will be to get the message to ordinary Nigerians about the urgent need to cull birds, prevent poultry movement and disinfect farms. Dick Thompson, of the World Health Organisation, responded to a report that Nigerians had been seen retrieving dead chickens from a pit of culled birds by saying it was a “really scary activity and something not been seen before”.
Neighbouring countries are also moving into action. This week a meeting was held in Senegal to try to establish a regional strategy for containment. Money should be available. Last month $1.9 billion was pledged by countries and international groups for the fight against avian flu—half a billion more than expected, which underscores the extent to which the disease is seen as a global threat. Infection across Africa would increase the likelihood that the virus will mutate to become transmissible between humans. But there is another vital dimension: the loss of farm income and of a vital source of protein could also be devastating for Africa. That ought to be food for thought for Europeans worried about a few dead swans.
|
| « Last Edit: Mar 6th, 2006, 11:21pm by Webcreeper » |
 Logged |
|
|
|
|
BBS
Help
Search
Members
Login
Register
Reply
Send Topic
Print