The 2009 H1N1 flu, better known as the "Swine Flu", first caused a great scare in North America in the spring of 2009. The fact that this virus didn't have a vaccine at the time of its emergence partly caused that scare, and made the very utter of the name spine-chilling, and the occurrence of the virus in one's region or state dreaded. The virus, which first began as an epidemic in Mexico, has since then had a low occurrence rate both nationally and globally, with the aid of vaccinations and treatment. However, during recent weeks there have been increasing reports of occurrence of the virus in the southeastern region of the United States, which causes the need of education and awareness of the virus, which is the intent of this paper.
Scientists studying at Oxford University found that the viral strain, H1N1 influenza A, derived from several strains of influenza circulating in swine, hence the common name "Swine flu" (1). The CDC believes the virus to be the result of reassortment, which is a process through which two or more influenza viruses can swap genetic information by infecting a single human or animal host (8). The virus later became known as 2009 H1N1, after being found to be very similar to the virus that caused the 1918 Flu Pandemic. In fact, there is only one amino acid change difference between the two. This change keeps the 2009 H1N1 flu in the upper respiratory tract, while the 1918 H1N1 flu infects the delicate tissues of the lower respiratory tract, thereby making it more deadly. Moreover, the results of those scientists studying at Oxford showed that this particular viral strain, which had already been found to be circulating among pigs, had possibly been circulating among multiple continents, for many years prior to its transmission to humans (1).
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Generally, the influenza virus, which is an orthomyxovirus, is a Baltimore class 5 virus with a negative ssRNA genome. It can survive for hours outside of a host, and causes respiratory infections. The genome is present in eight separate segments of ribonucleoprotein, all of which has to be present for successful replication (5). It has a helical nucleocapsid, whose major protein is the nucleoprotein, a protein which interacts directly with the RNA of the genome (4). The envelope is a lipoprotein that carries two types of protruding spikes, the neuraminidase (NA) and the haemagglutinin (HA) (5). There are nine antigenic types of neuraminidase and thirteen types of haemagglutinin, all of which are used to classify each strain of influenza. Furthermore, the haemagglutinin functions during attachment of the virus particle to the cell membrane (5). The genomic characteristic of influenza (it being negative) prohibits it from being translated into protein to produce the required polymerases, limiting RNA synthesis to only occur using a RNA-dependent RNA polymerase present in the virus particle (4). Researchers have found that antigenic shift, which is the major change in the surface glycoproteins of the influenza virus, leads to worldwide epidemics of influenza known as pandemics. Each pandemic strain carries HA and NA proteins that have been absent in humans for many years, and therefore immunity is either very low or nonexistent (2). This ultimately causes for the need of constant production of new vaccines. This antigenic shift has been found to be the result of reassortment.
The virus enters the cell via endocytosis. Once inside the low pH environment, the lipoprotein envelope fuses with the lipid bilayer of the vesicle, releasing viral RNP into the cell cytoplasm, from which it is then transferred to the nucleus. New viral proteins are translated from transcribed messenger RNA, as mentioned in the previous paragraph. New viral RNA is encapsidated, and along with new matrix protein, is then transported to sites at the cell surface where envelope haemagglutinin and neuraminidase have been incorporated into the cell membrane. The progeny virions are then formed and released by budding (5).
What set apart the 2009 H1N1 influenza A virus from the seasonal A (H1N1) virus is that the 2009 virus has been found to be more pathogenic than the seasonal virus. Studies were conducted in the summer of 2009, and scientists found that the replication of the seasonal A virus was found to be confined to the nasal cavity of subjects, but the 2009 A(H1N1) influenza virus also replicated in the trachea, bronchi, and bronchioles; and, virus shedding was more abundant from the upper respiratory tract for 2009 H1N1 influenza. All of this, and the fact that aerosol and respiratory droplet transmission is very efficient, suggests that the 2009 H1N1 influenza virus has the ability to persist in the human population, potentially with more severe clinical consequences (6). Emerging first in Mexico then appearing in the United States, the virus was able to spread to over 30 countries by human to human transmission during its first weeks of surveillance (7). Moreover, the virus seemed to hit hard during the fall, with 95% of all cases occurring between October 17 and November 14, 2009 (8). In 2009, the largely affected group was adults ranging from ages 18 to 64. It had the most cases, from about 19 million to 38 million cases, with a range of 27 million. There were about 121,000 hospitalizations, and about 7,450 deaths (8).
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The symptoms of influenza are generally characterized by fever, myalgia, headache and pharyngitis (5). This means that if you are infected with 2009 H1N1, then you will experience some of these symptoms, because it is similar to other strains of influenza, the only difference is that it has different receptor proteins. The vaccine, which was developed sometime after the first occurrence, was made to extend throughout the spring of 2010. While everyone is recommended to get the vaccination against this virus, the CDC highly recommends that pregnant women, people who live with or care for children younger than 6 months of age, health care and emergency medical services personnel, anyone 6 months through 24 years of age, and people ages of 25 through 64 years of age get vaccinated, because they are at higher risk for 2009 H1N1 influenza because of certain chronic health conditions or compromised immune systems (8). Anyone who is 10 years of age or older is only recommended to get one vaccination, while children from 6 months to 9 years of age are recommended to get two doses. Moreover, a regimen has been developed for children with severe asthma and people who are allergic to eggs, in order to make sure they are protected from being infected with the virus (8). Furthermore, researchers have found that both the 1918 and 2009 H1N1 influenzas could lead to the production of new vaccines.
In addition to a vaccine, there are also antiviral for the 2009 H1N1 influenza virus. These antiviral drugs can make you feel better, shorten the time you are sick, and prevent serious flu complications. These antiviral drugs can only be prescribed by physicians, and are highly recommended to those groups mentioned in the paragraph above, even if tests results are negative (8). Tamiflu is the brand name antiviral drug that is used to treat the flu, and the most common side effects that it has are nausea and vomiting (8).
At the start of 2010, the CDC estimated that approximately 47 million people had been infected with 2009 H1N1 between April 2009 and November 2009. Of those 47 million people, approximately 213,000 had been hospitalized, and about 9,820 deaths were reported (8). With that being said, the 2009 H1N1 flu should be taken very seriously because it has caused the first flu pandemic in 40 years. It is serious not only because of its new emergence and causation of serious infection to humans, but also because our bodies aren't familiar with the strain, probably because of the fact that it was a result of reassortment. People should also be made aware of the seriousness of this virus because of its similarities to the influenza strain that caused the 1918 Flu Pandemic, which killed 50 million people worldwide. This idea alone should inspire people to go out and get the vaccination. The influenza strain that caused the 1918 Flu Pandemic was able to infect the lower respiratory tract, which made it deadly, and if we can continue to get vaccinations and stop the spread of the 2009 H1N1 virus, then maybe it won't mutate or evolve to that point of infecting the lower respiratory tract. Vaccinations should also be given to prevent the further spread of the virus, thereby preventing more cases, hospitalizations and deaths in regions and countries that have a limited supply of the vaccine. People shouldn't mistake this as a just a flu virus, because even the most common flu viruses are dangerous, but most circulating in the population today are the 2009 H1N1, because of the easiness of the virus to do so.
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"Similarities Between 1918, 2009 H1N1 Viruses Could Lead to New Vaccines." RT For Decision Makers In Respiratory Care. Date Unknown. Web. 30 March 2010.
Dimmock, N.J. et al. Introduction to Modern Virology. 6th ed. Malden, Mass.: Blackwell Publishing, 2007. Print.
Keen, Anthony. "Influenza". University of Cape Town, 1995. Web. 31 March 2010.
Munster, Vincent J. et al. "Pathogenesis and Transmission of Swine-Origin 2009 A(H1N1) Influenza Virus in Ferrets." Science 24 Jul 2009: 481-483. Online.
Smith, Gavin J. D. et al. "Origins and evolutionary genomics of the 2009 swine-origin H1N1 influenza A epidemic." Nature 11 Jun 2009: 1122-1125. Online.
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"H1N1 Flu (Swine Flu): General Information." CDC.gov. Centers for Disease Control and Prevention, n.d. Web. 29 March 2010.