Experts point to migratory birds as culprits behind Japan's bird flu outbreak

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Experts point to migratory birds as culprits behind Japan's bird flu outbreak

Bird flu has been spreading across Japan, with cases showing up from Hokkaido in

the far north, to Kyushu in the south. Confirmed infections in both wild and

domesticated birds have jumped suddenly in late January, with five new cases

identified on just the 25th and 26th of the month.

While calls for measures to prevent the further spread of the disease are

increasing in tandem with the rising number of cases, there are also significant

worries about how the influenza crisis will affect Japan's food supply. Why is

the virus now spreading so quickly?

Bird flu is a disease originating in poultry birds like ducks and chickens, but

migratory wild birds are thought to be " smuggling " the virus into previously

unaffected areas. In wild ducks, for instance, after infection, the flu virus

has about a 10-day incubation period before the animal begins to show symptoms

-- 10 days in which the duck can travel for hundreds or even a thousand

kilometers.

" Wild ducks that were probably infected by domestic poultry birds on mainland

East Asia have, after their breeding season, come to winter in Japan and the

Korean Peninsula, " says University of Tokyo ornithology professor Hiroyoshi

Higuchi. Furthermore, Higuchi adds, the genotype of the virus infecting birds in

Japan is very similar to that found on the mainland, and it is now widely

believed that migratory birds brought the disease to this country.

Experts are split as to why there are so many bird flu cases this year, with

some saying the jump is because the virus has become more widely established in

East Asia, while others believe particularly cold winds on the Asian mainland

have forced more birds and more bird varieties to cross over to Japan than

normal.

The Ministry of the Environment has pointed out that the number of wild bird

species vulnerable to influenza now in Japan has risen to 33. These birds spend

winter in spots all over the country.

" No matter where infections are confirmed in this country, there is nothing

mysterious about how it got there, " says Yutaka Kanai, chief researcher at the

Wild Bird Society of Japan.

However, the virus may also be spreading via smaller wild birds such as sparrows

and even mice with infected bird droppings stuck on their bodies introducing the

virus into domesticated birds' supplies of drinking water.

With an eye to this very risk, in 2007 the Japan Livestock Industry Association

issued a 50-point livestock breeding hygiene checklist, including: " Have you

installed bird nets with mesh of two centimeters or less? " " Are you eliminating

mice? " " Are you changing into special clothes and footwear before entering the

poultry house? " Meanwhile, the animal hygiene section of the Ministry of

Agriculture, Forestry and Fisheries has added, " Invasion by a virus can be

prevented if all the points are put into practice to a reasonable extent. "

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