A number of patients have asked me recently about the flu virus that has been killing people in Asia. They are concerned that it might show up here, and they are right to be.

What is happening in Asia is almost certainly the beginning of what will become the next in a series of influenza pandemics that seem to sweep the world every 30-40 years. The World Health Organization now says it is inevitable.

The virus that appeared last December is an avian flu, an endemic infectious disease of birds. It spreads to people, usually by contact with poultry, when the avian flu virus hybridizes with a human flu virus. There is no vaccine and no effective treatment.

Thought to have originated in China, this flu spread quickly into Vietnam and Thailand. More than 150 million suspect chickens have been killed in an attempt to stop it, but the strategy has failed utterly. Flocks are now infected from western Russia to Japan to Malaysia.

Perhaps even more worrying for those of us who live in the west, the H5N1 virus has been found among wild geese in northwest China, and their migrations will almost certainly carry the disease to Europe. A team of American scientists is even now checking waterfowl in Alaska as they arrive on their migration from Siberia.

Despite such grim auguries, only about 60 people have died so far. But that’s because infection still requires contact with sick birds. For the disease to turn into a pandemic, the virus will have to mutate yet again, perhaps many times, into a form that can be passed directly from person to person. And that may already have happened: a family of three died in Jakarta in late July, having had no known contact with infected birds.

Much of this, of course, is speculative, because the evolution of flu viruses is always unpredictable. Consider, for example, the 1918 flu, by far the worst pandemic of the 20th century.

It began in Spain – hence the name “Spanish influenza” – in February of that year as a normal three-day flu. But it was unusually infectious. World War 1 was still being fought, and with people everywhere on the move, the virus spread all round the world.

By summer, it appeared to have run its course. But in late August, the virus mutated, concurrently, wherever it had spread. It was like no flu seen before or since. The faces of victims turned brownish purple, their feet black. Their lungs turned flaccid and they literally drowned in a bloody fluid. It killed not just young children and the elderly, as influenza usually does, but made a special target of strong healthy people in the prime of life.

And most ominous of all, from our perspective today, while the 1918 flu killed 2.5 percent of its victims – estimates range from 20 to 100 million, nearly all in just three months – the flu brewing in Asia today has a horrific mortality rate of 75 percent, worse even than Ebola and more than seven times that of SARS.

But to repeat, flu viruses are unpredictable. This current form may yet mutate into something much less dangerous. Meantime, your best defense is probably to lay in a stock of flu antiviral, which doesn’t prevent infection, but can mitigate its effects.

As for getting a flu inoculation this fall, whether it will work against this flu is purely a shot in the dark.

©Dr. Ashely Gordon, 2005.