Avian Influenza Virus and the Media

“How Scared Should We Be?”; Time, October 17^th, 2005, pp30-34.

The current form of avian influenza virus has been named H5N1 by virologists, after two proteins that dot the surface of the virus (hemaglutinin and neuraminidase).  The virus is generating fear among the population of the United States.  The possibility of a national or even global avian flu pandemic is relatively high, according to the article.  Recent natural disasters (hurricanes Katrina and Rita) served to deliver the message that without adequate preparation, the nation could descend into chaos in the event that transmissible avian influenza virus arrives in the United States. Millions of people will die when, and not if, the virus finally mutates into a more easily communicable form than exists at present.  Resistance to novel forms of the influenza virus (all of which originated as avian strains) is extremely rare, and new strains emerge every year.  Strains possessing the capacity to penetrate human cells are usually similar enough to normal human flu viruses for peoples’ immune systems to cope, but occasionally a form of avian influenza virus will infect humans while retaining all of its previous avian characteristics.  Under these unprecedented circumstances, there is no resistance, and a pandemic is inevitable.  References to the flu pandemic of 1918 have been made by the president of the United States and other high-ranking government figures, as a warning of what may happen, but solutions are not clear.

The current avian influenza strain has not exhibited a great ability to vector between humans; its victims have mostly been people who live or work in close physical proximity to birds.  When it does infect a person, the virus resides deep in the lungs, which is detrimental for the individual but diminishes the possibility of its being spread to other people.  Antiviral medications such as oseltamivir (Tamiflu) require administration within 48 hours of onset, and it is thought that preventative vaccines would be far more effective in the event of a pandemic.

The virus has been tracked as it moves across Asia toward Europe, infecting and killing thousands of birds along the way.  Wild ducks in particular are considered major distributors of the virus.  Human casualties have been restricted to Southeast Asia, Hong Kong, Indonesia and Malaysia, where a total of 67 people are believed to have died as a result of the virus.  Hong Kong was the site of the first infection of H5N1 in 1997.

The U.S. Department of Health and Human Services maintains a website dedicated to answering questions about pandemic influenza.  The website acknowledges that the H5N1 strain was first recognised in Hong Kong in 1997, infecting 18 people and killing six.  Tamiflu is suggested as a possible treatment, and the website states that research is underway to develop new vaccines and ways to generate larger quantities of vaccine more rapidly than at present.  The journal Nature (October 2005) states that human-to-human transmissions of avian flu have not yet properly occurred, but that half of the 120 people who have contracted the virus have died.  The journal describes how scientists have recently resurrected the 1918 strain from a lung snipping (Time also describes this), saying the strain is “the most bird-like of all mammalian flu viruses.”  The 1918 strain had never previously infected humans, and all eight of its genome segments were radically different from anything scientists had before seen. National Public Radio (NPR) described the U.S. as being “slow off the mark” compared to countries like the U.K, with regard to national preparedness for a major outbreak.  NPR’s Richard Knox stated that antiviral medications were going to be difficult to obtain, and production was considerably slower than required.  WHO identifies wild ducks as a “natural reservoir of avian influenza viruses” and says that these birds are most resistant to infection.

Viruses are acellular microorganisms and as such are not capable of replication outside a host cell.  They compose few essential macromolecules, possessing DNA or RNA and protein.  The avian influenza virus consists of 10 proteins and 8 strands of RNA.  It is encapsulated in a protein and lipid shell, some of which bind to receptors on the outside of cell membranes in airways and lungs.  The chemical affinity for the membrane enables the virus to penetrate cell membranes, and emerge into the cytoplasm, where the shell opens, releasing the RNA.  The RNA moves through the nuclear membrane into the nucleus, where complementary copies of it are made that then return to the cytoplasm.  This mRNA interacts with the ribosomes in the cell, and copies of the viral proteins are synthesised.  Inside the nucleus, complementary copies of the complementary copies are made, resulting in versions of RNA identical to that which was initially released into the cell.  This RNA returns to the cytoplasm, bonds to the newly synthesised proteins, and a new individual virus is generated.  The virus “buds” on the outer membrane, exits the cell and is either expelled by a cough or a sneeze, or else penetrates another cell in the airway to begin the process anew.  In time, this process overwhelms the cells, and they die, resulting in an excessive mucus load and sore throat.  Too many dead cells in the lungs (as in the case of H5N1) can result in death.

Time, as well as the U.S. Department of Health and Human Services, may be overemphasising the dangers of the avian virus H5N1 being spread by birds.  Medical professionals in the regions where the most birds have been identified with the virus are certain that the virus has not yet mutated, and is not capable of spreading from human to human.  It is difficult to believe that a virus responsible for 60 deaths globally in over eight years, and which thus far has been contracted only by people living in close proximity to birds, could cause “millions” of deaths in the United States.  The U.S. government has announced “prevention measures” involving the purchase of 20 million doses of Tamiflu, whose individual treatments cost $100 each.  The government’s enthusiastic urging of people to obtain Tamiflu may be connected to private interests (Donald Rumsfeld, Defence Secretary, holds a large portion of stock in the company that manufactures Tamiflu.  Roche, the manufacturers of Tamiflu, have refused to suspend the patent of the medication, after it was suggested that this would be a way for other pharmaceutical companies to help keep up with the demand, saying that other companies may require more time to develop the appropriate methodologies).  Time described the migration of the virus in terms that suggested a deliberate assault on the western world.  The truth is, the further west the birds migrate, the less chance there is that humans will be living closely with poultry.  Virulent strains of influenza kill individual birds in the wild, before they have an opportunity to travel far and infect a large number of other individual birds.  In this fashion, wild birds reduce influenza to a mild version of its original form.

The pandemic of 1918 was most likely caused by the unusual conditions of the First World War, when hundreds of thousands of humans were forced to live in close proximity.  These conditions created the ideal spawning ground for the deadly influenza of the time.  People, (soldiers in particular) packed into all manner of trenches, trucks, service vehicles, hospitals and locomotives, were infected.  The deadliest strain found novel conditions in which to proliferate.  As one scholar has said, “to be as virulent as the 1918 pandemic, the new strain needs its own Western Front.”  Today’s crowded Asia provides a similar environment, albeit not as concentrated or stressed, but nevertheless vulnerable to an impact from the avian strain.

The crux of the issue lies in the genetics.  The Time article stated the root of the name H5N1, but failed to connect the significance of the name for the avian flu to its epidemiology.  The surface proteins on the virus are the means by which antibodies recognise a virus from previous exposures, and are thus of extreme importance.  Viruses are named for these properties, which express information relating to the hemagglutinin and neuraminidase proteins coating the virus.  It has been suggested that the mechanism governing the genetic expression of the influenza virus may be cyclic; the eight RNA fragments disassociate and recombine according to a specific pattern, and it is a matter of time before a lethal combination occurs again.  Random events are a more likely cause.  Time briefly mentions the possibility of “genetic mixing” (recombinant genes) in the event of a person simultaneously contracting a human and animal virus – an event known as major antigenic shift, wherein two different strains combine and are unrecognisable to human antibodies.  This would be required for the virus to become pandemic.  The H gene would have to be changed completely, in order for a wholly novel form of the virus to be generated.  Scientists in Vietnam recently (Sunday November 13^th, 2005) announced a major antigenic shift of surface HA and NA molecules, decoded in both humans and animals, from cases in Asia.  The name “bird flu” is scientifically redundant, when the origin of the virus is considered, but in this educated age it will be no comfort to victims of a human pandemic to be aware of where the pandemic sprang from.

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