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Rodents suspected in spread of avian flu
02/16/2007
THE ASAHI SHIMBUN
Scientists suspect rats spread the recent outbreaks of avian flu at four farms in Miyazaki and Okayama prefectures after the H5N1 virus strain was brought over by migratory birds from China.
The experts agree that the migratory birds triggered the infections at the four poultry farms over the past month. But they said at a meeting Wednesday that the way the disease spread indicates that other factors were involved.
Inspectors found that nets and coverings were in place to prevent large migratory birds from coming into contact with the poultry.
In addition, dead chickens at three of the farms were found in areas farthest from the entrance of the coops, so the wild birds were not likely the direct source of the infection.
"It's possible that small rodents, such as rats, carried the virus into the chicken coops," said Toshihiro Ito, a professor of veterinary microbiology at Tottori University who chairs the team of specialists.
He said the rats were likely infected by the wild birds from China.
The task force, appointed by the Ministry of Agriculture, Forestry and Fisheries, said the H5N1 strain at the four farms was identical to the one that killed thousands of wild birds at Qinghai Lake in western China starting in 2005.
The strain was also similar to one found in duck droppings in South Korea in January.
"It is possible the virus was brought to western Japan by a route that went through China and the Korean Peninsula," Koichi Otsuki, a professor of veterinary microbiology at Kyoto Sangyo University, said.
According to specialists, migratory birds follow three main routes in winter. One route passes over Hokkaido, another crosses the Sea of Japan and the third goes through the Korean Peninsula.
Ducks are believed the likely carriers of avian flu because most ducks are not affected by the disease.
However, the avian flu virus multiplies in the intestines of ducks and is released in their droppings.
An Environment Ministry study confirmed that wild ducks were within a 10-kilometer radius of the infected farms in Japan.
Nets and other measures at the farms in Japan should have been enough to keep out large wild birds, like ducks, but rats and small birds could still enter the coops.
If the specialists confirm that rats were indeed the carriers of avian flu, it would be very difficult to avoid similar outbreaks.
"While it is necessary to prevent intrusion, it is also important to strengthen the resistance of poultry by reducing stress on the birds and improving ventilation (in the coops) to diffuse and inactivate the virus," said Hiroshi Kida, a professor of veterinary microbiology at Hokkaido University.
As to whether the virus might mutate into one that affects humans, Nobuhiko Okabe, director of the Infectious Disease Surveillance Center of the National Institute of Infectious Diseases, said, "While there is no need to become overly concerned, we also cannot let our guard down."
He said early discovery and culling of infected poultry should keep the possibility low of mutations in Japan. (IHT/Asahi: February 16,2007)
http://www.asahi.com/english/Herald-asahi/TKY200702160217.html
Rodents suspected in spread of avian flu
02/16/2007
THE ASAHI SHIMBUN
Scientists suspect rats spread the recent outbreaks of avian flu at four farms in Miyazaki and Okayama prefectures after the H5N1 virus strain was brought over by migratory birds from China.
The experts agree that the migratory birds triggered the infections at the four poultry farms over the past month. But they said at a meeting Wednesday that the way the disease spread indicates that other factors were involved.
Inspectors found that nets and coverings were in place to prevent large migratory birds from coming into contact with the poultry.
In addition, dead chickens at three of the farms were found in areas farthest from the entrance of the coops, so the wild birds were not likely the direct source of the infection.
"It's possible that small rodents, such as rats, carried the virus into the chicken coops," said Toshihiro Ito, a professor of veterinary microbiology at Tottori University who chairs the team of specialists.
He said the rats were likely infected by the wild birds from China.
The task force, appointed by the Ministry of Agriculture, Forestry and Fisheries, said the H5N1 strain at the four farms was identical to the one that killed thousands of wild birds at Qinghai Lake in western China starting in 2005.
The strain was also similar to one found in duck droppings in South Korea in January.
"It is possible the virus was brought to western Japan by a route that went through China and the Korean Peninsula," Koichi Otsuki, a professor of veterinary microbiology at Kyoto Sangyo University, said.
According to specialists, migratory birds follow three main routes in winter. One route passes over Hokkaido, another crosses the Sea of Japan and the third goes through the Korean Peninsula.
Ducks are believed the likely carriers of avian flu because most ducks are not affected by the disease.
However, the avian flu virus multiplies in the intestines of ducks and is released in their droppings.
An Environment Ministry study confirmed that wild ducks were within a 10-kilometer radius of the infected farms in Japan.
Nets and other measures at the farms in Japan should have been enough to keep out large wild birds, like ducks, but rats and small birds could still enter the coops.
If the specialists confirm that rats were indeed the carriers of avian flu, it would be very difficult to avoid similar outbreaks.
"While it is necessary to prevent intrusion, it is also important to strengthen the resistance of poultry by reducing stress on the birds and improving ventilation (in the coops) to diffuse and inactivate the virus," said Hiroshi Kida, a professor of veterinary microbiology at Hokkaido University.
As to whether the virus might mutate into one that affects humans, Nobuhiko Okabe, director of the Infectious Disease Surveillance Center of the National Institute of Infectious Diseases, said, "While there is no need to become overly concerned, we also cannot let our guard down."
He said early discovery and culling of infected poultry should keep the possibility low of mutations in Japan. (IHT/Asahi: February 16,2007)
http://www.asahi.com/english/Herald-asahi/TKY200702160217.html
