TOKYO: Japanese health authorities on Thursday said a fifth outbreak of bird flu since November had hit a poultry farm in the central region of Aichi, as local officials began a cull of 150,000 chickens there.
Since November Japan has confirmed five cases of bird flu at farms in four of the country's 47 prefectures. Some 600,000 chickens have been culled.
The flu has also hit Kagoshima and Miyazaki prefectures on southwestern Kyushu island, which are major poultry farming areas.
In Miyazaki, a foot-and-mouth outbreak last year forced the slaughter of almost 300,000 farm animals.
European scientists have found a way to genetically modify chickens so that they don't transmit bird flu, according to research published on Thursday in the journal Science.
Bird flu, also known as H5N1 avian influenza, usually afflicts poultry but can cross over to humans and cause lethal respiratory problems and other complications.
The first cases detected in humans were in Hong Kong in 1997. A wider global outbreak took hold in 2004 and cases have flared across parts of the world ever since.
Scientists from the Universities of Cambridge and Edinburgh said the modified chickens could get bird flu but could not pass it on to other chickens.
"Chickens are potential bridging hosts that can enable new strains of flu to be transmitted to humans," said Laurence Tiley, of the University of Cambridge's Department of Veterinary Medicine.
"Preventing virus transmission in chickens should reduce the economic impact of the disease and reduce the risk posed to people exposed to the infected birds."
However, Tiley noted that the research still in its early stages, and the birds they developed are not intended to be eaten by people.
"The genetic modification we describe is a significant first step along the path to developing chickens that are completely resistant to avian flu," Tiley said.
"These particular birds are only intended for research purposes, not for consumption."
The birds were altered by a new gene that makes a "decoy" molecule that imitates an element of bird flu virus.
Then the virus is "tricked into recognising the decoy molecule instead of the viral genome and this interferes with the replication cycle of the virus," the study said.
When scientists infected the genetically modified chickens with avian influenza, the birds fell ill but did not spread the flu to other birds, whether those birds were genetically modified or not.
"The results achieved in this study are very encouraging," said researcher Helen Sang of the University of Edinburgh.
"Using genetic modification to introduce genetic changes that cannot be achieved by animal breeding demonstrates the potential of GM to improve animal welfare in the poultry industry," she said.
"This work could also form the basis for improving economic and food security in many regions of the world where bird flu is a significant problem."
One of five wild ducks found dead in South Korea this week was on Saturday confirmed to have been infected with a lethal strain of the bird flu virus as the country battles its first outbreak in over two years.
Tests showed the five dead birds found in Sacheon City on December 26 had been stricken with the H5N1 virus, the agriculture ministry said in a statement.
The same strain - which poses a risk to humans - has also been detected in wild birds and their faeces at four other locations across the country since December 7, it said.
South Korea on Friday confirmed the outbreak of bird flu and more than 100,000 birds have been slaughtered as authorities seek to contain its spread.
Two poultry farms, one in the central city of Cheonan and the other in the southwestern city of Iksan, were confirmed to have been contaminated, the ministry said.
Health authorities placed a quarantine zone over a 10 kilometre (6.25 mile) radius, restricting movements of vehicles and people and carrying out emergency disinfection.
They have also stepped up inspections of wild birds and urged poultry businesses to take extra precautions such as erecting nets around their farms to keep wild birds out.
The avian influenza outbreak is likely to further strain the country's health system, which has already been struggling to contain swine flu and foot-and-mouth disease (FMD) cases across the country.
South Korea has been hit by avian influenza three times, with the last outbreak in April 2008.
In 2008, South Korea had to cull more than eight million birds to curb the virus, resulting in damages estimated at 200 billion won (194 million dollars at the time).
Four people were confirmed to have been infected with the bird flu virus in late 2003 in South Korea but they showed few symptoms, health authorities said.
Lethal bird flu strain confirmed in S.Korea wild duck