Containing the dangerous bird flu

The Asahi Shimbun, Asia News Network, Tokyo

So far, there have been no signs that the bird flu virus that killed thousands of chickens at a farm in Yamaguchi Prefecture is spreading further in Japan.

The steps that have been taken to contain the outbreak, such as slaughtering chickens that may have been infected and banning movements of chickens and eggs in nearby farms, have apparently proved effective. The first outbreak of avian influenza in 79 years in Japan has raised the specter of another big health scare, but, fortunately, it is not developing into an epidemic here, at least at the moment.

With regard to the infection route, experts have suggested that migratory birds may have brought the avian flu virus into Japan. But the theory has yet to be proved. What is clear is that this or other viruses could somehow find their ways into Japan in the coming years.

To prevent a future epidemic, there should be effective systems to discover symptoms at an early stage, carry out tests quickly and publish relevant information for swift actions to contain outbreaks. Both chicken farmers and the livestock hygiene authorities in Japan should remain on the alert for telltale signs.

The H5N1 virus strain, which was detected in Yamaguchi, has struck a huge number of birds and prompted massive poultry culls in Vietnam and South Korea since late last year. The World Health Organization has confirmed that the disease has infected and killed several people in Vietnam. In a Hong Kong outbreak in 1997, the H5N1 strain killed six out of 18 people who were infected.

In the reported cases, however, there is as yet no evidence of human-to-human transmission. It is believed that the virus spread directly from sick birds to people. And health experts think the virus doesn't have a very strong ability to hop easily from birds to humans.

There is no documented case of human inflection through eating chicken or eggs, according to the Ministry of Agriculture, Forestry and Fisheries. Since viruses cannot survive high temperatures, poultry products should cause no fear when they are heated sufficiently before eating.

What is worrisome is the possibility that the virus could mutate or combine with a human flu virus to gain the ability to spread from person to person.

The notorious influenza of 1918-1919, known as "Spanish Flu," the most devastating epidemic in the 20th century, infected 600 million people around the world and killed 23 million. There have been a number of other global flu epidemics, if not as severe as the Spanish Flu. Influenza viruses are believed to originate in birds.

Wild birds are affected by a variety of flu viruses, and some of them latch on to human flu virus to become a new strain that spreads between people, according to the widely accepted theory. Many scientists think this process occurs within the bodies of pigs. Some strains, they point out, could jump the species barrier between birds and humans.

No new human influenza virus has been detected since the Hong Kong flu virus was discovered in 1968. Scientists have been warning for 10 years that a new virus can appear at any time. The bird flu virus that is spreading in Asia is one of those that are believed to be able to become a new pandemic influenza strain.

Viruses can easily change their pathological characters by mutating or mixing genes with other viruses. A new virus capable of human-to-human transmission could rip through a population with little natural immunity, and when one is discovered, developing an effective vaccine and test kits to confirm infection quickly is crucial to preventing the spread of the disease.

There are also effective preventive measures everybody can carry out easily. Try to maintain good health conditions and gargle and wash your hands constantly. These efforts go a long way toward the prevention of not only bird flu but SARS (severe acute respiratory syndrome) as well.