Michael Richardson: Turkey trials crucial to halting pandemic

The spread of bird flu to an increasing number of people in Turkey is raising concern that the virus will mix with human influenza, change into a form that can spread easily from person to person, and trigger a global epidemic.

The World Health Organisation emphasises that so far there is no evidence this deadly mutation has occurred in Turkey or elsewhere. It says human cases are caused by close contact with infected birds, usually chickens and other poultry kept in backyards or homes during winter.

It also says that all people diagnosed with the H5N1 avian flu virus in Turkey - at least 15 cases have been confirmed - are being treated with antiviral drugs.

But what will happen if the H5N1 virus mutates so that it can pass quickly from person to person?

For some time, WHO has been working on a plan to extinguish local outbreaks of the H5N1 virus among clusters of humans before the flu, which is normally highly infectious, can ignite a pandemic. Turkey is an important test case.

The prospect of halting a pandemic at its source or delaying its international spread is attractive but it has never been tried before. WHO still needs more time to finalise a global intervention plan but it hopes to do so soon.

Last August, it was promised 3 million doses (amounting to 30 million capsules) of Tamiflu, one of two antiviral drugs considered most effective in reducing the severity of illness in people caused by H5N1.

This stockpile is the basis of the organisation's plan. Tamiflu's maker, Swiss-based Roche Holdings AG, has promised the first one million doses will be ready early this year, and the remaining two million before the middle of the year.

Epidemiologists say it is in a race against time to prepare for a pandemic. Vaccines offer the best protection but they must be tailormade to match any new strain of influenza when it emerges and infects humans. This can take up to six months.

Governments and pharmaceutical companies are now giving priority to research and processes that will shorten the time needed to mass produce flu vaccines. The results of this work must be shared so breakthroughs can be rapidly harnessed.

If everyone is to be protected, about 6.5 billion doses of vaccine must be produced and administered.

The absence of an effective vaccine to protect populations creates a gaping hole in global pandemic defences. Neither of the two available anti-viral drugs, Tamiflu and Relenza, prevents or cures infection by an H5N1-like pathogen, although they may help to reduce the severity of illness if taken within 48 hours after symptoms begin.

The best hope of containing any human pandemic may be to place stockpiles of anti-viral medicines in the hands of WHO and the national governments of countries it considers are particularly vulnerable.

Cluster

The aim would be to rush the drugs to any area where a cluster of human-to-human cases is detected in the hope that it can be isolated until a safe vaccine can be mass-produced, distributed and administered.

WHO says that for intervention to be successful, several conditions must be met:

1. The first viruses that can jump from human to human will not yet be highly contagious and will be limited to a small geographical area.

2. The first clusters of human flu cases will be rapidly detected and reported.

3. Antiviral drugs from the stockpile will be administered quickly to all of the affected population.

4. Movement of people in and out of the areas will be effectively restricted.

Given the unpredictable nature of influenza viruses, it is impossible to know if the first condition will apply, and the remaining conditions will depend heavily on the willingness and ability of national and local authorities in the country concerned to co-operate with WHO. So far, Turkey seems to be doing this.

In China's case, government leaders clearly recognise now what is at stake. But when you have more people and more farm poultry and more mixing of humans and birds than any other country, it is a difficult situation to control.

Indonesia, too, is struggling to improve its animal and human health surveillance.

After an inspection tour of Liaoning, one of the Chinese provinces hit by bird flu, China's Premier Wen Jiabao admitted the country was facing a "very serious situation" in controlling the epidemic.

Preventing the disease from jumping to humans would be an "arduous" task, he added.

* Michael Richardson, a former Asia editor of the International Herald Tribune, is a visiting senior research fellow at the Institute of South East Asian Studies in Singapore. He is the author of Bird Flu & Bio-Security: Is the World a Dead Duck? See www.iseas.edu.sg (link below) and click on Viewpoints.