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The Unexpected Threatening MurdererThe threats, details and prospects of the Avian Flu
Kim Ja-eun  |  jaeunkim@yonsei.ac.kr
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승인 2014.03.04  23:22:42
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ONCE AGAIN the threatening murderer has returned, causing chaos in South Korea. The first time this murderer made its grand appearance was in the winter of 2003-2004, killing 5 million. The next appearance was almost exactly three years later, in the winter of 2006-2007, also causing the death of 2.8 million. Then, in the spring of 2008, it again struck the lives of 10 million. It didn’t finish there. 3.5 million were also killed in the year 2010 -2011. The ruthless criminal taking the lives of innocent birds is no other than, the Avian Influenza (AI), also known as the bird flu.

 

   
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The Infamous H?N? Family

           What is the bird flu? The bird flu is an illness caused by an influenza virus in poultry. When poultry are infected with bird flu, they will show symptoms, such as lack of coordination, energy and appetite or suddenly dying without any signs. Currently all poultry of areas contaminated with this virus, are culled in order to stop the virus from spreading wider into other areas. This also reduces all possibilities of this virus infecting people, which are very rare, but not impossible.

Before getting into the details, there are endless possibilities for different variations of the flu. So, how many variations of this flu have we witnessed recently? Though there are endless possibilities for different variations of the flu, the main types of the flu that are drawing attention around the world are H5N1, H7N9 and H5N8. The extremely pathogenic virus, H5N1 carries a very high possibility of becoming a deadly disease among poultry.  Chronologically, the H5N1 was the cause of the previous four deaths of poultry in South Korea, in the years of 2003-2004, 2006-2007, 2008 and 2010-2011. Although this virus does not usually affect humans, in 2003, in Southeast Asia and North Africa a total of 648 cases were reported, from which 348 people died and represented a death rate of 59%. These people who were sick or died were infected only as they made direct or close contact with infected poultry, both living and dead. It is also likely that they showed symptoms of the flu, such as severe respiratory illnesses, diarrhea, and fever. Prevention of the H5N1 includes staying away from sick or dead poultry and consuming properly cooked, over boiling temperature, poultry and eggs. Fortunately, there is no evidence that this virus spreads from person to person.

           However what is catching the current attention of the people, in other words, what seems to be threatening peoples’ lives, is not H5N1. It is the relative, H5N8. H5N8 has a very high possibility of being the result of mutation between the virus H5N1 and H?N8 (unknown H). H5N8 is the cause of the mass deaths of poultry currently in South Korea. Yet this is not the first appearance of H5N8 into the world. It was first discovered on a turkey farm in Ireland, in 1983. Decades later, in 2010, an infected wild duck was diagnosed with the virus in China. However, in both cases people were not infected. Hence the avian flu occurring in South Korea is not dangerous to people at this point, as well.

Another strain of the virus that is currently coexisting with the H5N8 is the H7N9. The H7N9 is residing in China only, but it is highly dangerous to people. A total of 135 human cases with H7N9 were first reported, out of which 45 people died. Fortunately, no cases of infection between people have been found. Although the H7N9 virus is a mutation of the avian flu, cases of sick poultry with the H7N9 virus were rarely found. Therefore this strain of the virus is currently being considered more as the human flu, especially since there seems to be no pathogenicity found in poultry.

The Mutation and Spread of the Flu

           Stepping away slightly from all the different types of the flu, one may ask the essential questions such as how do the flu viruses change? How have these viruses been created? The answer is mutation. There are two types of changes that can happen to the viruses. One of them is antigenic drift, a rather slow change to the flu virus. This is a genetic change, in which the antibody already existing inside of the host latches with a new flu virus, goes through a genetic mutation within and loses its immunity. This would be the reason to why people need new flu vaccine every season. The antibody that one received through a previous flu shot has a high chance of losing its immunity, through securing itself with a new flu virus. Before the flu gets any worse, new flu shots with fresh antibodies must be received in order to fight the flu virus.

The second type change is antigenic shift. The antigenic shift is a sudden change when the two different types of flu strains combine into one host, such as a chicken or pig, and infect the same cell together. As a result, this may create new flu subtypes which would also allow the mutation of the new subtype to infect humans from animals. This shift is the cause of spread from animals to humans. Hence, the mutation into this new flu subtype could become the cause of pandemic, to which people do not own the immunity of.

Infection, or spread, is caused by the antigenic shift in three ways. The first antigenic shift is when the bird strain from a poultry and the human strain from a human combine together in one cell of a chicken or a pig, then spread to humans. The second antigenic shift occurs when the bird strain from a duck or other aquatic bird directly affects the human. The last antigenic shift happens when the bird strain from a duck or other aquatic bird infects another animal host, such as a chicken or a pig, then moves on to the human. Through the following three ways of the antigenic shift, humans can be infected with the flu from animals.

Fear Factor of the Flu

           Returning to the current issue of the flu virus H5N8 in South Korea, why is it causing such fear when it appears to cause little danger to people? 

   
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This question can be answered through the geological location of South Korea and the current presence of the viruses H5N8 and H7N9. First of all, the virus H5N8 is located in South Korea and the virus H7N9 is present in China, a neighboring country of the Korean peninsula. Thus, the characteristics of a possible pandemic are all concentrated within this area. The possible pandemic can occur from the mutation of the viruses H5N8 and H7N9. As discussed previously, H5N8 is the virus of an avian flu and H7N9, of a more human flu. If an infected bird with the virus H5N8 or person with H7N9 approaches towards the other virus and gives the possibility for mutation, Pandora’s Box for a new pandemic will be opened. This possible pandemic is especially dangerous because the immunity for this pandemic does not exist yet. Hence, this means that the mutation of H5N8 and H7N9 could become the ultimate murderer of not just a single country, but of the world. Both of the countries must be very cautious of this possible catastrophe from becoming a reality.

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           The unexpected entrance of the flu is causing the fear of many because of its possibility of being the gateway to a pandemic, with no solution. The H5N1 and H7N9 are highly pathogenic viruses of the avian flu that actually killed people, unlike the H5N8 that hasn’t involved a human case yet. However, the H5N8 is also a part of the fear factor due to its possibility of creating a cureless pandemic with the H7N9. However the chances are still at suspense – the murderer is just behind the door. Hopefully the murderer will quietly pass by again, just like its antecedents.

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