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The evolution of man does not only evolve within his entire boundaries. Other entities are capable of such matrix, in which man continually has tried to figure out. In the field of medicine, various quests have been made that mostly concerns the health and sickness related cases to look for treatments that directly points to an extension of man's life span. Within this progression, further discoveries have been laid to fully understand the nature of life, specifically to alleviate the intrusion of fear especially when it comes to the various elements that continue to threaten the lives of many.
In relation with fear, numerous factors have continually invoke such, just like the presence of viruses and its complexity and hidden mysteries have somehow become an alarming concern not only among the medical experts and researchers, but as well as the ordinary people. The previous decades of medical history has been longed known to be a massive search on the complexity of viruses, and primitive experiments were even done to find answers and possible treatments. However, the present times have depicted a representation of myriad unfolding phenomena, which has perhaps insinuated that viruses will be presently evolving as the time passes. Nevertheless, it is not intended though, to assess the huge works inculcated by many individuals that have invested their lives to viral related studies.
Thus, elaborative measures can be implied to further understand the processes of scientific studies concerning viruses, its types and classifications, epidemiology or strategies as what this paper might suggest-but primarily focusing on the single branch-the Influenza A virus. As discussions will be presented, this study also tackles on the core concepts of viruses and then on the Influenza type, as to present significant information or may imply correlative efforts in whatever purpose it may serve.
The Concept of a Virus
It is generally considered that for one to understand the concept of Influenza, definitions of "virus" itself would be tackled. As such, certain accounts would be rational enough to establish a definite view. For one, Goudsmith (1) listed important facts about viruses that are considerably of great substance, selectively discussed in the following:
There exists 3 families in the living world namely bacteria, archaea and eukarya.
Humans are said to be more acquainted with the organism bacteria, unlike the archaea which unknowingly exist in the ancient times; eukarya contains a nucleus that are present in every living organism, whether single-celled, like paramecia and amoeba, or multi-celled-all the plants, animals and even the human beings. Thus, viruses are cited as parasites and premises on whether they are alive or not are continually on a debate.
Living beings are described as an independent entity that is separated from its environment.
The cell is known as the basic unit of life. Its cell parts are separated and working independently for the proper functioning of the body processes. For example, the cell's mitochondria together with the organelles can be compared to the kidney and the heart's functions; the nucleus carries an important program that handles all the cell behavior and characteristic, in which the wall membrane enclosing it also serve as a receptor. The cell is also structured with a DNA or RNA that can replicate itself manifested in all living organisms and the viruses as well.
Viruses have the tendency of being living.
As seen under the electron microscope, it is cited that the virus have similar features that of a cell-mainly a shell or protein coat enclosing or a nucleus-like attribute with DNA and RNA patterns, in which unlike the human basic cells, are incomplete. This makes the virus cells incapable of reproduction that it needs a host or another cell for it to spread and multiply. Its penetrative characteristic is somewhat brought about by a cell machinery, often referred to as infection that is often unnoticed and may either be infectious or not. Therefore, this makes the virus more of a transitional entity for it has an incomplete capacity to be independent and be totally alive; yet it has the capacity, in one single move, to reproduce again.
Viruses are quiet undead.
As cited, it cannot be constantly concluded that virus particles are alive, that is why technically, they do not undergo extinction. Viruses may endure a state of replication and duplication with only its DNA or RNA code, enough for survival and be in contact with other living cell. Additionally, its protein coat makes it hard to exterminate and its facility to multiply fast in an enormous way makes it more difficult.
Viruses possibly have an everlasting existence.
With the constant reality that everything in this earth shall pass, the bacteria possess a natural diversity that makes it continually live. On the other side, it is assumed that viruses are owned by each life form, that when their original hosts have reached extinction, they will jump to other possible descendants; for example, from the dinosaur to the reptiles. This case merely implies that viruses will always look for means to continue to exist, even if they venture into other hosts or combine with other types of viruses as well.
Viruses usually waves out to the world for survival.
If the viruses loses its original, the chimpanzees for the HIV virus for example, it tends to look for possible alternatives and the humans are highly not excluded of the possibility. This is so because of the cell structure both animals and humans might resemble, but more risks are far being placed.
A virus is "a piece of nucleic acid surrounded by bad news" stated by a Nobel Prize awardee biologist, Peter Medawar (2). With the stated nature of viruses, there is definitely an indicative nature of the appearance of negativity that in return creates threat in the survival issues of humans. The major component of DNA and RNA makes the virus a more complex component that continually challenges the medical field.
Additionally, viruses are considered to be belonging to a life form that is in between the peripheral vicinity of life and death, which can reproduce with the aid of an external host or other cell (1). The presented arguments on the varied characteristics of viruses relate the basic notion on the virus's structure, which somehow relates to the uniqueness it possesses among any other life form.
On the other hand, the virus has major classification system that enables the clear identification of a more specific virus type. These are usually based on it the nucleic acid component and its propagation mode, namely (3):
Class I - which are double stranded DNA; with examples like the papovavirus (cervical cancer or warts), herpesvirus (genital herpes, cold sores), adenovirus for respiratory illnesses, and poxvirus for smallpox or cowpox.
Class II consists of single stranded DNA, like the parvovirus.
Class III classifies the double stranded RNA, like the reovirus causing diarrhea
Class IV - a positively single stranded RNA that also acts as mRNA; like the coronavirus, hepatits C, picornavirus (common colds, poliomyelitis), togavirus (yellow fever)
Class V - negative single stranded RNA used as a template for mRNA synthesis; such as the rhabdovirus for rabies, paramyxovirus for mumps and measles, orthomyxovirus which includes the influenza viruses, bird flu and swine flu; arenaviruses and bunyaviruses for the Koean hemorrhagic fever.
Class VI - a DNA intermediation in replication with a positive single stranded RNA; like the retrovirus for AIDS and leukemia.
Class VII - an RNA intermediate in replication with a double stranded DNA found in the hepatitis B virus.
Subsequently, the DNA or deoxyribonucleic acid is identified as molecule containing genetic information, with two polynucleotide strands forming a double helix; and was discovered by Fritz Miescher, a Swiss physician (4). While the RNA or ribonucleic acid has similar chemical structure with DNA but exists in a single strand although it is capable of creating a double helix (4). On the other hand, the mRNA contains "a sequence of the nucleotide bases" namely: (A) Adenine, (C) Cytosine, (G) Guanine, and (T) Thymine-that are labeled as "message" because "the cytoplasm of a cell translates mRNA into a protein by interpreting each sequence of 3 nucleotide bases into an amino acid that forms the protein" (3). The so-called positive-stranded RNA is said to have the capacity to serve as a messenger RNA or mRNA, since it has the capacity to sense a message. Meanwhile, the negative-stranded RNA needs the nucleotide bases complement message sequence where "cytosine (C) is complementary to guanine (G), and thymine (T) is complementary to adenine (A)" (3).
These facts related to viruses somehow depict the complexity of life's inner processes though it also promulgates certain threats to the basic human nature. Thus, the long history of finding key medications and cures, starting from the ancient experiments for vaccines until the contemporary researches on possible medicine intakes for viruses. There will still be a long journey to be undertaken, but it all starts with basic knowledge and understanding.
The Influenza Virus
Perhaps, one of the most common and known form of a virus is the influenza. The influenza virus became known as Spanish influenza-not because it originated in Spain, but because the country had uncensored reports on the disease's widespread that killed 170,000 of their population (5). Moreover, it had also reached other countries like Europe, Africa and Asia passing through chief seaports such as "Freetown in Sierra Leone; Brest, France; and Boston, Massachusetts" (6). In the same way, influenza is also known as seasonal influenza, caused by an influenza virus and is basically identified in the form of common colds.
The World Health Organization (7) has presented key facts and helpful information regarding seasonal influenza:
It is an acute infection that can easily spread among persons.
It affects any age group in any parts of the world.
It usually peaks during cold seasons that cause annual epidemics.
It is regarded as a serious health and public matter for it can lead to severe sickness and worse, death.
It also affects the economic stability of a certain nation for it can lose the productivity of workforce and can sprain health services.
It can be effectively prevented by vaccination.
Categorically, one can instigate how easy it is to capture influenza in general and as being described as a seasonal flu. Originally taken from the animal accounts, the virus seemed to be easily taken as easy as breathing. Indeed, this form of virus has taken advantage of natural hosts, with an amazing fact that it has been rooted in a deep history; and has traveled across many countries-thus, depicted from its Italian term that roots from the word "influence" (5).
Types of Influenza
There are basically three types of influenza virus, namely: type A, B and C that are further elaborated in the following (3, 7-9):
These types are known to cause major pandemic and are usually classified according to its protein subtypes and different combinations. Although they are stressed as a common influenza form, these types are said to be the scariest among the three, with the fact that it has historically caused a massive and most serious cases. It is said that it can contaminate most on people and animals like birds, pigs, horses or whales, yet its natural host are the wild birds. Type A influenza are divided into:
H5N1Â Subtype - bird flu virus
H3N2Â Subtype - Hong Kong flu pandemic of 1968
H5N2Â Subtype - highly pathogenic in chickens
H3N8Â Subtype - frequently found in horses
H2N2Â Subtype - Asian flu pandemic of 1957
H7N7Â Subtype - 2003 poultry epidemic
H1N1Â Subtype - Spanish flu pandemic of 1918 and swine flu
The H1N1 type of influenza has currently feared most nations and severe cases were even noted. Aside from this, H1N2 and H3N2 are also circulating among the different parts in the world.
It has a milder effect than type A though it can also cause an epidemic disease. They are usually found among humans but are not classified according to subtype.
The type C influenza virus only produces mild infectious illnesses, as with common cold and thus is not connected to any epidemic or pandemic phenomena. They are also "antigenically stable and cause only sporadic disease" (3) and are frequently to occur. Type C do not have subtype classifications and is said to have not been included in seasonal influenza vaccines unlike the types A and B.
Influenza Virus Structure
The image (10) above is the structure of influenza virus and is typically seen with a rough or spherical structure and is termed as the influenza virion. The virus's outer layer, called lipid membrane is subject to the host's cell for it to multiply thus indicating influenza is an enveloped virus. The insertions are called spikes or glycoproteins that are known as HA or hemagglutinin and NA or neuraminisdae. These proteins determine the virus type (A, B, C) and subtype (A/H1N5). The proteins HA and NA are said to be important determinants for the creation of possible immune antibodies as these may protect the bodies from infection. Another part is the M1 or matrix or viral protein that gives a strong force, and the rigidity of the shell or lipid envelope. The genetic materials within the virion are viral RNAs, 8 are for the influenza A.
Two important cell parts of the influenza virus are the hemagglutinin and the neuraminidase. These are protein cells and enzymes that impart the important activities within the virion. The hemagglutinin is the protein that attaches the virus to the infected cell, in which 16 are labeled as H1 and H16; their molecules are a mixture of three identical proteins that will form an "elongated cylindrical shape" (3). While the neuraminidase are aids the virus to infringe the walls of the cells; they are also known as sialidase for its capacity to break links between the "sialic acid and cellular glycoproteins and glycolipids in cell walls" (3). Neuraminidase consists of 9 subtypes labeled as N1 up to N9; and usually forms a mushroom-like protrusion on the top portion of the influenza.
Influenza Virus Changes: Drift and Shift
There are two ways that determine the change in influenza viruses: antigenic drift and antigenic shift. Antigenic drift takes place via minor changes but its occurrence continue over time that might even produce new virus strains, unrecognizable by human antibodies (8). One example is the flu virus that continually occurs in different periods of time, as it may have developed new strains of viruses that presently are not recognized by the bodies' antigens. It is also due to mutation with less number of epidemics or sporadic outbreaks (10).
Meanwhile, the antigenic shift is the sudden and major transition of viruses that results to a combination of either both the hemagglutinin and neuraminidase proteins and the hemagglutinin protein (8). These new protein combinations were not apparent in the human conditions for many years. Thus, the occurrence of new influenza A virus is the outcome of this antigenic shift. This will then possibly result to a pandemic threat, since human bodies does not yet have the capacity to produce antigens against the new type of virus.
Air is the main vessel in the widespread of Influenza A viruses. This reflects that the virus usually affects the respiratory organs that may complicate other organs as well. If a person is infected with flu, common colds or cough, he might contaminate other people as well by simple sneezing or coughing especially if the person is vulnerable and unprotected. This is because the viruses are transmitted in droplets that can easily penetrate through the nose or mouth. Aside from this, persons who have contacted surfaces or basic things like knobs or telephones, can also be elicited to possible victims especially if they have handled such-from the hands passed thru the mouth or nose. The virus has an incubation period of 18 to 72 hours (10). Additionally, the seasonal influenza can easily multiply through towns, homes or even schools. This makes the children even more at high stake of capturing the virus despite that it can affect all age groups. Aside from this, persons with low immune system, the children and old alike are more prone to later complications.
On the other hand, other influenza A viruses can be transmitted with the aid of the animals. As original settlers of viruses, the birds or ducks can transmit the virus through other animals as well like the pigs, which more likely to bring it to humans (1).
The onset of fever, colds and running nose apparently directs to the symptoms of common flu. Aside from these symptoms, the onset of headaches, massive malaise, joint and muscle pains and sore throat, also indicates seasonal influenza (7). Other signs also include shaking chills, chest pain or coughing that produces thick and yellowish-green-colored mucus (9). However, influenza can also cause severe damage among high risk individuals like the children and the old such as convulsions or ear infections and even death if not treated.
In addition to these, the following are a more detailed list of the symptoms and complications of influenza viruses (11):
38-40 degrees fever
Headache or myalgias
Photophobia, tears or ache (ocular symptoms)
Nasal discharge, dry cough
Gastro-intestinal symptoms like vomiting and diarrhea (also in H1N1 strain and 2009 swine flu)
Acute laryngotracheobronchitis or croup for children with a "barking seal" cough, breathing difficulty, stridor or crowing sound during respiration
Secondary bacterial infection (Streptococcus pneumoniae, Staphylococcus aureus, Hemophilus influenzae)
Myositis (type B influenza, seen mostly among children)
Encephalopathy (that caused major deaths in Michigan in 2002-2003 flu season)
Reye's syndrome, serious infection on the liver and brain that may result to coma; that may also incorporate vomiting and lethargy.
Guillain-Barré syndrome or acute idiopathic polyneuritis, a mysterious syndrome in the central nervous system, that may be followed by a bacterial or viral infection
Clinical studies show that children are more prone to type A influenza viruses. The young often lack the needed antibodies because of lack of exposure and the diameter size of their respiratory tract makes it more difficult since swelling and inflammation are likely to block the sinus or respiratory system (11). Thus, their immune system is still developing, aside from other external factors like malnourishment and environment aspects. This makes the children a candidate for a higher fatality rate; while the elderly suffer it due to decreased immune system effectiveness.
However, there are several options to help prevent, treat or at least ease the symptoms of the illness. Flu vaccines more like prevent the flu, together with non-medical alternatives; over-the counter treatments alleviate it but antivirals effectively do all the tasks (9).
Moreover, the World Health Organization (7) recommends vaccination as an effective tool in preventing the illness. As such, there have been available safe and effective vaccines for about 60 years. The influenza vaccine is also said to prevent the influenza-specific vaccines between 70%-90% among fit adults; reduces 60% of possible complications and severe illnesses among the elderly; and, decrease deaths by 80%. Furthermore, WHO recommends vaccination among those who are at higher risk of serious influenza impediments, even those are responsible for caring high-risk individuals; also with the following:
Residents at the nursing home comprised mainly of the elderly and disabled
People suffering from chronic diseases
Pregnant women, health care workers, people with essential functions in the society and the children from six months to two years
Viruses are considered to be multifaceted and compound structures that continue to threaten the ordinary lives. The different historical accounts and stories behind the huge efforts made by the scientists prove man's unraveling conquest to further understand the phenomena and mysteries of human nature.
With the presence of such complexity, illnesses like the influenza and its type need to be of great concern to continually push through further studies for its constant cure or remedy. Especially that the present times depict an enormous advantage of uncertainties, there lies variations of medical and health related fears. Yet it cannot be denied that the famous "prevention is better than cure" represents a reality of man's awareness and prevention efforts on the certain diseases that threatens his survival. Perhaps, health organizations and medical personnel should work hand-in-hand for the information drive of the various diseases, like influenza. With this, not only are the ones who are academically involved in such topics but as well as the ordinary individuals. Though it may have thought that influenza A is just a common cold, the death and treatment tolls indicated that it should be just taken for granted.
Other means to prevent the illnesses are also suggested to be utilized, with the aid of proper awareness, correct food intake and physical exercise.