Peter Curson: Human bird flu could kill millions

Opinion

The epidemic of bird flu sweeping through Asia threatens to become a global health crisis of huge proportions. The world has not seen an outbreak of this disease on such a scale before and already it has devastated large parts of Asia.

Once again, the world's health authorities are talking about a pandemic with dreadful effects on human and animal health.

Asian countries are yet again mobilising their resources to educate the public and to try to eradicate the disease.

Last year probably more than 150 million chickens and ducks were destroyed as part of containment programmes. Today the epidemic is most severe in the broad wetlands of central Thailand and in the Mekong and Red River deltas in Vietnam, home to huge populations of migratory aquatic wildlife.

In Vietnam, where tens of millions of ducks, geese and other waterfowl are raised in backyard farms, major culls are under way as well as restrictions on breeding programmes.

When bird flu came to world attention in 1997 and 2003, there were fears that if the virus came into contact with human flu and recombined or mutated we could pay a heavy price.

If this happened in the context of a local environment marked by dense concentrations of people, chickens, pigs, ducks, domestic and other animals, as well as aquatic wildfowl, the world was looking at a cataclysmic health event.

Why this has not yet happened remains something of a mystery, given that the virus has had ample opportunity to combine with human influenza. Some think it is only a matter of time before a new, lethal and highly contagious disease is unleashed on the world.

If this happens, the most optimistic scenario sees between two and seven million deaths worldwide. The Daily Mail in London has claimed that up to 100 million people worldwide and 500,000 people in Britain could die.

For years world health officials have been warning that a new influenza pandemic on the scale of the 1918-19 one, which killed some 40 million people worldwide, including more than 8000 New Zealanders, was just around the corner.

World health officials are steeling themselves to the possibility, and a number of countries are beginning to stockpile anti-viral drugs and accelerating the development of potential vaccines.

In Europe, for example, countries are stockpiling anti-flu drugs and some countries have established protocols for vaccinating key workers.

The strain of bird flu known as H5N1 has killed 45 people in Southeast Asia over the past year and has led to the destruction of tens of millions of chickens and numerous wild birds and waterfowl.

So far the virus has shown considerable versatility in jumping species and has been found in pigs, domestic cats and tigers.

Bird flu has also turned out to be more infective than previously thought, although there is still no evidence that it can spread from person to person.

Like Sars, bird flu has raised issues of public confidence and a growing awareness of good government, transparency and accountability.

It also highlights the extent of poverty and injustice throughout Southeast Asia, where, in the case of Thailand for example, the process of culling chickens on poor rural farms with minimal compensation stands in sharp contrast to that of simply vaccinating birds on the big agricultural conglomerates near Bangkok.

It also further demonstrates that health and agricultural authorities often have difficulty getting co-operation, particularly in affected areas, and the lack of money, manpower and at times political will to put in place a range of simple measures designed to prevent the epidemic from spreading.

Bird flu is a classic example of a zoonotic infection (a disease of animals) which has probably existed in its natural host - waterfowl and migratory birds - as a fairly benign gastrointestinal infection for centuries in parts of South Asia. Huge flocks of ducks have largely pursued a nomadic existence in search of food and breeding sites throughout the region, often coming into close contact with domesticated and farmed chickens and ducks and other fowl.

The real reasons for the emergence of infections such as bird flu lie not in the seemingly random nature of the biophysical environment as they do in our behaviour, lifestyles, farming methods and general attitude to the environment.

Crowded living conditions, with people, animals, birds and wildlife all sharing living space, has encouraged viral intermixing and the emergence of new viral infections.

The lack of official oversight of farming methods and the poorly regulated use of antibiotics by farmers to raise chickens and pigs has contributed to increasing antibiotic resistance and the emergence of new disease strains.

Bird flu continues to devastate Asian economies.

For many households it has meant the loss of livelihoods and food security.

Backyard poultry raising is one of the few opportunities that poor urban and rural families have to supplement their meagre income and diet.

For countries exporting poultry products, the epidemic has also produced a major setback. Last year alone it is estimated that the total gross domestic product loss for Asia was between NZ$14 billion and $21 billion.

Bird flu poses a major threat to global animal and human health, requiring public health, agricultural and community interests to be aligned in a concentrated campaign to control the spread of the disease. If this does not happen, then we might be looking at 1918-19 all over again.

* Professor Peter Curson is director of the health studies programme at Macquarie University, New South Wales.