Japan: Cold snap 'forced flu-carrying birds south'
Tue, Feb 01, 2011
The Yomiuri Shimbun/Asia News Network

A wave of extremely cold weather this winter is a suspected factor behind the ongoing spread of avian flu in Japan, according to ornithologists.

Flocks of migratory birds infected with an avian flu virus may have arrived in parts of the nation after advancing farther south than in an average year, instead of wintering on the Korean Peninsula. Their arrival may have been an attempt to avoid a wave of cold weather in continental Asia that has intensified since the beginning of this year, experts said.

"The spread [of avian flu] may have become even greater as a result of these birds arriving in this nation after migrating through such highly virus-dense areas as Siberia, China and Mongolia," Hiroyoshi Higuchi, a professor of ornithology at the University of Tokyo, said.

The highly virulent H5N1 avian flu has spread nationwide. Cases of bird flu infection have been found in nine prefectures, including those that have come to light in four prefectures since early this year.

A huge number of infected chickens have been culled at poultry farms in these prefectures. However, there is no telling what can be done to prevent wild birds--a probable vector of avian flu infection--from contracting and spreading the disease. Scientists remain unsure about why the nation is witnessing such frequent occurrences of bird flu this winter, as well as whether the epidemic will continue to spread.

The spread of avian flu has forced the adoption of emergency measures by various institutions in Japan, including the Homeland for the Oriental White Stork, a prefectural park in Toyooka, Hyogo Prefecture. For years, the facility has been dedicated to the preservation and breeding of the storks, an endangered species.

Storks kept in the park were moved from roofless cages to ones covered with plastic sheets in the facility Thursday, two days after the body of a wild bird suspected of having the avian flu virus was found in Itami, also in the prefecture. The action was intended to keep these storks away from the droppings of wild birds that fly into the park, enticed by the feed given to the protected birds.

"There is no perfect way to prevent small birds from sneaking into the cages through their grids," Naoki Yamaguchi, an official at the prefectural government, said.

It is even more difficult to ensure that no wild bird that has contracted avian flu spreads its disease. This can be exemplified by the case involving nabezuru (white-headed cranes)--another endangered species--that were found to have been infected with the virus after arriving at the Izumi Plains in Kagoshima Prefecture to spend the winter there.

Alarmed by the incident, the Izumi city government has expanded the area in which migratory nabezuru cranes are allowed to be fed, by 50 per cent over previous years. The 1.5-fold expansion reflects concern that the presence of any crane infected with the flu could instantly spread its disease among other cranes if it stays in close proximity to them. While a larger area should reduce overcrowding, it is also feared that excessive expansion of the feeding area could make it easier for any infected crane to transmit its disease to other wild birds in the neighborhood.

Hamanakacho, eastern Hokkaido--where ohakucho (whooper swans) infected with the flu have been found--is home to tanchozuru (red-crowned cranes), another endangered species.

"Trying to catch [tanchozuru] and moving them to a safety zone would produce the opposite of the desired effect. Doing so would turn them away," an Environment Ministry official said. "All that can be done is to swiftly find and collect the bodies of cranes that have died of the flu and those that have grown weak because of the disease."

Chances are that the spread of the avian flu this winter has been caused by flocks of migratory birds--mainly wild ducks--that became infected with the virus in Siberia and other areas during a breeding period in the summer and have arrived in Japan to spend the winter here.

According to the ministry, there are 33 kinds of wild birds at high risk of infection, including wild ducks, crows and cormorants. Such birds inhabit all parts of the country.

"As circumstances stand today, the flu has not yet affected any wild bird that lives in Japan throughout the year. It would be difficult for the virus to exist [in the nation] from the spring onward, as temperatures of lakes and marshes begin to rise," Tsuyoshi Yamaguchi, a professor at Tottori University, said.

"The odds are probably low that the spread of infection will continue through the year," he said.

However, some scientists have issued a warning about the possibility of the ongoing epidemic resulting in a more ominous consequence. "Suppose migratory birds carry avian flu viruses into this country every year, and viral infection spreads among wild animals. This could increase the possibility that a bird flu virus could mutate into one that could affect humans," said Masato Tashiro, who heads the Influenza Virus Research Center at the National Institute of Infectious Diseases.

Govt streamlines response

The farm ministry has been desperate in its efforts to contain the ongoing spread of bird flu since the crisis struck.

"We should never repeat the same mistakes as committed in handling the foot-and-mouth disease [that hit Miyazaki Prefecture] last year]," an Agriculture, Forestry and Fisheries Ministry official said.

On Saturday, the ministry convened an emergency meeting of officials from Tokyo and all prefectural governments who undertake to deal with the epidemic. These officials were told to conduct on-the-spot inspections at major poultry farms under the jurisdiction of their local governments and ensure there are no holes in nets installed there to prevent wild birds from sneaking into these facilities.

However, some local governments have been embarrassed by the ministry's advisory. "It will be unrealistic to inspect all chicken farms," an official from the Shimane prefectural government said.

Such is also the case in Miyazaki Prefecture, where a number of bird flu cases have been reported. The prefectural government has 47 epidemic prevention officials in charge of such inspections. This means each official has 246 farming households to inspect, including those raising cattle and swine. The figure is fivefold the national average.

The farm ministry has said it will take prompt measures to cull infected chickens, realizing that its slow action to deal with last year's foot-and-mouth epidemic added to the damage suffered by cattle farmers.

This approach contrasts with the ministry's previous stance on infectious disease cases involving livestock. In the past, the ministry sent samples to government-run laboratories where genetic tests were conducted on them to determine whether the cattle in question were infected with particular viruses.

In addressing the ongoing crisis, however, the ministry now will take steps to cull infected chickens immediately after genetic tests are carried out by relevant prefectural governments to find samples test positive.

From Thursday on, the ministry further simplified these procedures. It has made such decisions only through abbreviated tests--without waiting for the results of genetic tests.

-- The Yomiuri Shimbun/Asia News Network

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