Is a flu pandemic imminent?
Despite massive culling by authorities to control the outbreak, the highly pathogenic H5N1 strain of bird flu continues spreading among the poultry in Bangladesh. A total of 47 districts out of 64 have been affected by this avian flu virus, and more than 50 percent of the poultry farms has been closed. This virus strain is regarded to be the most likely cause of the next human flu pandemic.
Influenza pandemics are natural, recurring events. They are somewhat rare but, like other natural phenomena, happen from time to time. A pandemic occurs on a much greater scale, spreading around the world and affecting people across many countries. Three flu pandemics have occurred in the last century: 1918 to 1919 (Spanish flu); 1957 to 1958 (Asian flu) and 1968 to 1969 (Hong Kong flu). Each of these pandemics affected large numbers of the population, causing millions of deaths and huge economic and social disruption. On the basis that the last flu pandemic was almost 40 years ago and that they occur every three to four decades, it would appear that we are overdue for such a global disaster. Therefore, we can only assume, the next flu pandemic is approaching. But is a pandemic, which has the potential to kill tens of millions of people worldwide, really imminent? And will H5N1 be the cause?
Experts fear that the H5N1 strain of avian influenza A could trigger the next pandemic for a number of reasons. H5N1 is a severe highly pathogenic form of bird flu, which has been affecting poultry flocks and other birds across the world since 2003. But the virus is not simply confined to birds. It has already demonstrated an ability to infect people and cause severe disease, one of the key characteristics of a pandemic strain. Since it first emerged, there have been 366 cases of infection in people who have had close and direct contact with infected birds. But the consequences of an H5N1 pandemic could be much worse because it is so lethal, if that strain did cause a pandemic, it could be something as bad as 1918 or even worse. In the 1918 pandemic 50 million people died worldwide from a population on the planet of just over one billion people. The virus also has the ability to mutate and acquire genes from viruses infecting other species. Experts are worried that the virus could either adapt, giving it greater affinity for humans, or exchange genes with a human flu virus, thereby producing a completely new virus strain capable of spreading easily among people, and causing a pandemic.
The World Health Organization has developed a global alert system, based on six pre-defined phases, as a way of signalling the seriousness of the risk of an influenza pandemic. The world is currently at phase III, meaning that a new influenza virus subtype is causing disease in humans, but is not yet spreading efficiently among humans. We don't know when the next pandemic will begin, how long it will last, how severe it will be, or which flu virus will cause it. We just know it's coming.
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