Cuban efforts bolstered

bird flu but were not diagnosed because their symptoms were too mild. The findings suggest some populations have developed natural resistance to the virus. The study of more than 45,000 people in Vietnam, reveals that up to 750 people are likely to have become infected with the strain after handling sick birds. Anna Thorson, who led the study, said the real figure potentially extended into thousands. The cases were not picked up because, while people developed coughs and a fever, they either failed to seek medical help because their symptoms were mild, received treatment from unregistered practitioners or were missed by the doctors inspecting them. The researchers studied interviews with more than 45,000 people in FilaBavi, a Vietnamese demographic surveillance site with confirmed outbreaks of H5N1 in poultry during April to June 2004. Eighty-four per cent lived in households that kept poultry and more than 25 per cent reported birds falling ill or dying of flu in that time. Of those between 650 and 750 people suffered flu-like symptoms after handling the birds. Although there are some questions about the study and the difficulty in diagnosing symptoms in such a rural community, the work has raised new issues surrounding the virus. The outbreak in Turkey has also raised questions about the apparent mildness of the virus in some cases in this country. Part of this may have been the result of medical care which included the administration of anti-viral drugs such as Tamiflu but other explanations for why the Turkish death rate has been lower have not been discounted. It could be, for instance, that people in Turkey are more resistant to the virus than some of the Asian populations. Or perhaps Turkish authorities were able to detect cases more quickly. Gene-sequencing information can confirm where the victim caught the disease — and so far that seems in every case to be from birds directly. “It’s not clear yet that the situation we’re observing in Turkey, the number of infections, the virulence, is any different than what we’ve been seeing in Vietnam,” says the MRC’s Alan Hay. Professor Peter Dunhill, an expert on vaccines for avian flu at University College London, said rural communities in Vietnam have been living with bird flu for more than 10 years and may have developed resistance to it. “It may well be that there is some immunity in Turkey too.” Recent developments in Turkey and other countries on the eastern edge of Europe have prompted calls for the establishment of a European task force that can be mobilised to fight the virus. Albert Osterhaus, a virologist at the Erasmus Medical Centre in the Netherlands and chairman of the European scientific group on influenza, believes more coordination is needed in Europe to tackle bird flu. “I think we should form a European influenza task force that brings together all our knowledge, so that if you have outbreaks in the future you could form delegations to work together with local experts in the area where it occurs,” he told a meeting in London last month. But other researchers believe the new findings and the current pattern of bird flu, the human infections and human influenza may mean that a pandemic is still some time away. While that may give government authorities a little more breathing space, there is growing consensus that, if the H5N1 strain leads to the next human pandemic, the consequences could be catastrophic. Writing recently, Neil Ferguson, a specialist in infectious disease epidemiology at Imperial College London said: “the odds are that there will be no human pandemic in the next five years. However, this is no reason for complacency or a reduction in preparedness planning. As the emergence of a pandemic is, in essence, a chance event, we cannot predict exactly when the next pandemic will strike or how severe its consequences will be. That it will strike eventually is certain.” Current Biology Vol 16 No 3 R66