Bird Flu: Who Is at Greatest Risk of Dying?by Bradford Frank M.D., M.P.H., M.B.A.
Avian influenza or "bird flu" has now caused more than 60 deaths worldwide, with the most recent epidemic in Indonesia, where four people have died. On a global basis, 60 deaths are not very many. So why are health experts becoming alarmed about the H5N1 ("bird flu") virus? People are concerned because the virus has demonstrated the ability to kill a high percentage of the humans it infects. In addition, it has spread from birds to many other species, which is very uncharacteristic of viruses. The spread of infection in birds increases the opportunities for direct infection of humans. If more humans become infected over time, the likelihood also increases that humans, if concurrently infected with human and avian-influenza strains, could serve as the "mixing vessel" for the emergence of a novel subtype--with sufficient human genes to be easily transmitted from person to person.
Once the virus acquires the capability to "go human," an influenza pandemic (that is, a worldwide epidemic) would likely ensue in a matter of weeks. To date, the vast majority of infections of bird flu in humans have been acquired by close contact with domestic poultry. However, there is one documented case of human-to-human transmission in Thailand. It remains a curious fact that most people who have worked with poultry infected with the bird-flu virus, culling infected birds for example, have not become infected--a fact that no one seems able to adequately explain.
The antigenic changes (that is, changes in the exterior proteins--Hemagglutinin and Neuraminidase) in bird and human influenza viruses go on year after year. Annual influenza outbreaks typically do not cause severe illness and death, because people have built up natural immunity to the viruses over a period of years. Rapid spread of H5N1 viruses between humans, on the other hand, will led to explosive global expansion in which everyone is at risk for infection, illness, and death because of a complete lack of natural immunity to the virus.
Because avian influenza or "bird flu" is much more deadly than the regular annual flu in humans, coupled with the high infectiousness of influenza viruses in general, a bird-flu pandemic is potentially very deadly, causing many tens--or even hundreds--of millions of deaths across the globe. In September 2005, Dr. David Nabarro of the World Health Organization (WHO) stated, "A new pandemic would claim between 5 million and 150 million people."
Once a flu pandemic starts, everyone will be at risk of getting pandemic flu, because no one has natural immunity to the virus. However, certain groups may be at greater risk of dying than others. There are strong indications that the coming bird-flu pandemic may be similar to the influenza pandemic of 1918 and, if so, healthy adults would be most at risk of dying, along with pregnant women and the elderly.
Why are healthy adults at greatest risk? It appears that the H5N1 bird-flu virus causes a massive immunological response against the virus in those with the strongest immune systems. Unfortunately, this causes the release of human enzymes called "cytokines," which destroy lung cells along with viral particles. This, in turn, causes a deadly outpouring of fluids into the lung, which interferes with the exchange of oxygen and carbon dioxide. This reaction is frequently fatal. There are few effective treatments--one of the only treatments available is to place the patient on a ventilator, a mechanical respirator. Even with this treatment, patients often die from complications.
About the Author: Bradford Frank, M.D., M.P.H., M.B.A. The Frank Group P.O. Box 138 Lakewood, NY 14750 (www.AvoidBirdFlu.com)
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To learn more about the potential impact of an influenza pandemic I recommend the following books:
1. America's Forgotten Pandemic : The Influenza of 1918 :
A fine, galloping account of the influenza pandemic that killed some 25 million people in less than a year. In some ways it was a page out of the Middle Ages bound in the twentieth century. No plague ever killed so many people in so short a time. Alfred Crosby has systematically covered the effect of influenza upon the armed forces, major cities, and American territories. Over and above this he has depicted the spread and impact of the disease over a good part of the world. The scariest aspect of this tale is that it is not fiction. It has already happened, and scientists not only foresee the repeat of such an apocalyptic scourge as possible, but they express surprise that it hasn't already repeated its destruction... yet.
2. The Monster at Our Door: The Global Threat of Avian Flu :
Avian influenza is a viral asteroid on a collision course with humanity. In 1918, a pandemic strain of influenza killed at least 40 million people in three months. Now, leading researchers believe, another world catastrophe is imminent. A virus of astonishing lethality, known as H5N1, has become entrenched in the poultry and wild bird populations of East Asia. It kills two out of every three people it infects. The World Health Organization warns that it is on the verge of mutating into a super-contagious pandemic form that could visit several billion homes within two years. In this urgent and extraordinarily frightening book, Mike Davis reconstructs the scientific and political history of a viral apocalypse in the making, exposing the central roles of agribusiness and the fast-food industries, abetted by corrupt governments, in creating the ecological conditions for the emergence of this new plague. He also details the scandalous failure of the Bush administration, obsessed with hypothetical "bio-terrorism," to safeguard Americans from the greatest biological threat since HIV/AIDS.
3. Flu : The Story Of The Great Influenza Pandemic :
Feeling tired, achy, and congested? You'll hope not after reading science writer Gina Kolata's engrossing Flu, a fascinating look at the 1918 epidemic that wiped out around 40 million people in less than a year and afflicted more than one of every four Americans. Could such a deadly flu appear again? Many scientists fear it could, hence their quick response to the 1997 outbreak of chicken flu in Hong Kong, which led to the slaughter of 1.2 million birds and, Kolata argues, averted another worldwide disaster. Clearly explaining both the science and the social toll of the pandemic, Kolata writes an admirable history and soberly spells out how the U.S. government is preparedAor unpreparedAfor a similar public health threat today.
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