The Desease Without Vaccine Free Essay Example

SARS is a highly contagious ailment, whose indications closely resemble those of influenza. Some of the symptoms of SARS are chills, headaches, muscle pains, sore throat and high fever. As the disease continues, there is an onset of pneumonia, which can prove to be fatal. In this context, the World Health Organization had estimated that fifteen percent of the cases of SARS infection proved to be fatal. This disease has defied all attempts at a cure; moreover, there is no vaccine for this disease.

The SARS virus underwent a mutation, which enabled to cross the species barrier from animals to people.

SARS is a respiratory illness and the symptoms of this illness are fever when the virus infects the human body. Normally the temperature of the human body of an infected person would be in excess of 100. 40F. The infected person develops chills and symptoms like headache, discomfort and body pains. In addition, there could be mild symptoms of respiratory distress in the beginning.

Within two to seven days the patient develops a dry and nonproductive cough. The nonproductive cough would result in insufficient supply of oxygen to the blood.

Some patients could even require the administering of clinical ventilation. SARS is a contagious disease and it spreads through the droplets that issue forth from a person who is coughing or sneezing into the air, if that person has been infected by the SARS virus. The primary manner of transmission of the virus is through the air or from objects that are contaminated with the virus (TARGET – SARS Target II SARS/CoV 3CL-PRO).

In 2003, an outbreak occurred of a previously unrecognized illness – termed SARS, or severe acute respiratory syndrome.

It was caused by infection with a newly identified coronavirus, SARS-COV. Infection produced an illness with Pneumonia as the main disease; however, some patients developed other complications like the loss of appetite, diarrhea and bleeding in the abdomen or stomach. Many of those who developed this disease were health-care workers and the infection rate among them was very high (SARS. Black’s Medical Dictionary, 41st Edition. CredoReference ). Extraordinary and exceptional isolation procedures had to be necessarily adopted because the Epidemic threatened to spread all over the world from its origin in Hong Kong.

Some of the measures adopted, in order to reduce the risk of the spread of this infection was the concentration of patients in individual hospitals, which were converted into isolation units. Visitors were not allowed into such hospitals. Staff and other patients who had been exposed to persons suffering from this disease were segregated in such special units. Further, routine care for in patients in the hospital was discontinued and screening of likely contacts was conducted. In addition, a number of restrictions were imposed on travel.

Due to this strategy, which had been performed in coordination with the World Health Organization, the SARS pandemic was finally controlled (SARS. Black’s Medical Dictionary, 41st Edition. CredoReference ). The virus genome on careful analysis revealed that this virus was a recombinant of virus relating to bird bronchitis and a virus relating to mouse hepatitis. It takes between two to ten days for the symptoms caused by the SARS virus to become noticeable after the infection takes place.

With the increasing age of the patients there is a corresponding increase in mortality rate and proves to be fatal in approximately half of the patients whose age is above sixty years of age (SARS. The Hutchinson Unabridged Encyclopedia including Atlas CredoReference). In the month of November 2002, the first incidence of SARS infection was discovered. This was in a place that was close to Foshan in the Guangdong province of southern China. However, this disease caught the attention of the people in the month of February 2003, when it spread globally due to air travel by infected persons.

In the month of February 2003, Carlo Urbani, who worked for the World Health Organization in Bangkok, was asked to go to Hanoi in Vietnam, in order to treat an industrialist, from the US, who showed symptoms of an unknown disease. In this manner, Carlo Urbani became the first person to identify this disease as a new disease (SARS. The Hutchinson Unabridged Encyclopedia including Atlas CredoReference). Several scientists, especially those from Canada, were successful in establishing that this new SARS virus belonged to the family of the coronavirus.

This disease spreads to other persons, if the victim is located very close to an infected person who spreads this disease by coughing. Further, this disease spreads to people who enter a place in which infected people have deposited exhaled droplets of phlegm or other fluids in their body. Moreover, infection with this disease occurs if contact is made with door handles and similar objects that have contaminated droplets on their surface. Furthermore, it is possible to get infected with this disease if a person enters an enclosed place like a lift in which contaminated droplets are present.

Eight thousand victims of SARS were identified by the end of is outbreak in the year 2003. Out of these SARS victims, seven hundred lost their life. The maximum damage due to this virus took place in China, Hong Kong and Taiwan. In Toronto, Canada there were one hundred and forty cases of such infection and twenty five of such infected persons died. In Singapore, there were around three hundred instances of this infection and out of these thirty persons lost their life (SARS.

The Hutchinson Unabridged Encyclopedia including Atlas CredoReference). In the year 2003 scientists were successful in discovering the gene that made the human body prone to infection by the SARS virus. While studying the human leukocyte antigen or HLA proteins, they realized that the variation in a gene that produces the HLA-B*4601 protein was common in the South China population. This was the area of origin of the SARS virus and people with this gene variation displayed a reaction to the SARS virus that was greater in severity in comparison to those who did not have this particular gene variation.

Moreover, SARS infections are very rare in people who do not possess this HLA-B*4601 gene variation. Most of the people who belong to Taiwan and Europe do not have this gene variation (SARS. The Hutchinson Unabridged Encyclopedia including Atlas CredoReference). At the time of the rapid spread of SARS, the World Health Organization sent out a global alert in which it asked the people to mask their face in public places, to avoid air travel, to thoroughly check airplane passengers for increase in body temperature and to quarantine infected persons.

A number of scientists are engaged in developing a vaccine for this disease. However, this disease was controlled by the beginning of the year 2005 and does not exist anywhere in the world, except in the laboratories (SARS. The Crystal Reference Encyclopedia CredoReference). SARS has defied all attempts at a cure and there is no specific vaccine for it. This has restricted the treatment to reducing the severity of the symptoms shown by the patient and treating any side effects of this infection (SARS in full severe acute respiratory syndrome.

Britannica Concise Encyclopedia CredoReference ). It is now common knowledge that in the year 2003, in Guangdong province of China, the first occurrence of this severe atypical pneumonia was observed. The epidemic was suspected to be associated with a new virus and subsequently, researchers isolated an avian influenza A (H5N1) virus from a patient in Hong Kong. Researchers focused on members of the Paramyxoviridae family since some particles were detected by the process of electron microscopy of respiratory samples from patients in Hong Kong and Frankfurt (Peiris, Chu and Cheng).

Subsequent investigations revealed that the human metapneumovirus or hMPV existed in SARS patients. Researchers in China had detected the Chlamydia organism in patients who had died due to atypical pneumonia during the outbreak of SARS in Guangdong. However, these organisms were not present in patients outside China. In the month of March 2003, researchers in the United States, Hong Kong and Germany found traces of a previously unknown coronavirus in SARS patients.

This discovery was in different ways and some of these methods included isolation on cell culture, demonstration by electron microscopy, demonstration of specific genomic sequence by polymerase chain reaction or PSR and by the use of microarray techniques and the indirect immunofluorescent antibody tests (Peiris, Chu and Cheng). In this context, the World Health Organization announced on the 16th of April, 2003, that the coronavirus had not been discovered in humans and animals till that date and that it was a new virus, which was the cause of SARS.

Before announcing the discovery of this new virus, thirteen laboratories in ten countries tested this new coronavirus in accordance with the postulates of Koch, which is essential to prove that this new virus causes SARS. This virus causes interstitial pneumonia that shows symptoms that are similar to SARS, and the virus was isolated from the nose and throat of infected monkeys. The corona viruses belong to the family of Coronaviridae. This family consists of very large, positive – sense single – stranded RNA viruses, which replicate themselves in the cytoplasm of the animal host cells (Siddell, Wege and Meulen).

The gene factors of corona viruses range in length from 27 to 32 kb, and are the largest of the RNA viruses. The diameter of the virions ranges vary from 100 to 140 nanometers. Most of the viral particles bear the distinct appearance of surface projections and these spikes extend to twenty nanometers from their base. In animals, corona viruses cause extremely virulent respiratory, enteric and neurological diseases. They also cause hepatitis, respiratory diseases that are temporarily prevalent and widespread in animals and gastroenteritis having short incubation periods between two to seven days.

The symptoms revealed in SARS are the same (Holmes). Corona viruses are species – specific and when they attack immunocompetent hosts, their infection extracts neutralizing antibodies and cell – mediated immune responses, which in turn kill the infected cells (Holmes). Most of the corona viruses cause terminal diseases in animals such as feline infectious peritonitis virus or FIPV, hemagglutinating encephalomyelitis or HEV of swine and some strains of avian infectious bronchitis virus or IBV and mouse hepatitis virus or MHV.

They replicate themselves in the liver, lungs, kidneys, gut, spleen, brain, spinal cord and other tissues (Holmes). Human corona viruses HCoVs were found to cause minor diseases. They are found in group 1 known as HCoV – 229E and group 2 known as HCoV – O43, and they cause minor respiratory problems (Makela). Sometimes they cause severe infections of the lower respiratory tract in children and adults and a condition termed as necrotizing enterocolitis in newborn babies.

They can survive on normal environmental surfaces for three hours and they are transmitted among humans by droplets, hand contamination, fomites and small particle aerosols (Ijaz). The Coronaviruses produce Coronavirus Main Protease protein or 3CL – PRO. This protein helps the virus to replicate itself and thereby spread the infection. In order to stop the infection, it is essential to bring about a disabling of the protein from working and this would consequently, contain the virus production and the attendant infection. Therefore, researchers had concentrated on producing a drug that would hinder the functioning of the 3CL – PRO protein.

With the achievement of this breakthrough, pharmaceutical companies started to prepare drugs that would hinder the functions of the 3CL – PRO protein, which is responsible for the multiplication of the virus and the resultant SARS infection. Ritonavir and Indinavir are the major ingredients of the anti – HIV drugs. The Coronavirus Main Proteinase is the principal drug that is used in the treatment of SARS (TARGET – SARS Target II SARS/CoV 3CL-PRO). The HIV virus and other viruses that cause influenza on infecting people have been described as wily because of their characteristic of mutating rapidly.

This trait helps them to obtain immunity from antiviral drugs or from the human immune system. However, the SARS virus has not been undergoing mutation. Clinical examinations of the genome sequences of fourteen isolates from patients in Singapore, Toronto, China and Hong Kong did not establish any mutations of the original sequence and it can be concluded that the SARS virus is invariant. However, this notion that SARS virus does not mutate or fails to mutate cannot be taken for granted since the virus did not face significant resistance from human hosts (Knight).

Coronaviruses are not so active in the replication of their genetic material and as a result they make one error for every ten thousand nucleotides that they replicate. This is similar to what the HIV virus does. Coronaviruses have a significant characteristic that helps them to reject mutations as and when they occur. These viruses have an enzyme that enables them to replicate their genetic material and spreads among several copies of the viral genome instead of being restricted to a single template of the genome.

The result of this is that each genome is copied from multiple templates. This procedure reduces the chances of mutations in the populations of the coronavirus (Knight). The enzyme that brings about the copying of the virus functions in such a manner that instead of using just one template genome it accesses several such templates and this results in a drastic reduction in the possibility that any particular mutation will dominate in a viral population. Moreover, such haphazard template access can entail an inaccurate access by the enzyme (Knight).

The consequence of such access by the enzyme would be the deletion of some portion of an essential gene, which could produce results that would be drastic, particularly, if the mutation affects the protein spikes that are bound to the surface of the viruses’ cellular victims. In 1984, there was an outbreak of a new ailment on European farms that were rearing pigs. It was determined to be a mutant of the coronavirus, in which the altered spike protein had effected changes in respect of the type of cells that could be invaded by the virus.

Although, this mutant did not prove to be fatal, all the same it has spread globally and made the diagnosis of gut disease more difficult (Knight). It is assumed that genetic deletion was responsible for the SARS virus to find a new target, namely, the human body, from its previous animal hosts. In that case the mutation could be of a totally different type due to the fact that the spike protein has remained unaltered.

While comparing with the viral strains present in the animals sold in the Chinese markets, it became evident that the SARS virus does not have twenty nine nucleotides in the gene for a protein whose function could not be determined. This protein was found to be appended to the inside of the protective layer of the virus (Knight). The WHO spearheaded the battle against SARS and was extremely successful in uniting the global community in combating this menace. Dr Carlo Urbani became a martyr in the battle against SARS.

This disease demonstrated that there are several dangers that could surface when least expected to do with terrifying results (SARS: how a global epidemic was stopped). Within a short period of seven months, around eight thousand people were infected by this disease in twenty nine countries. 1755 persons were infected in Hong Kong and of these 299 succumbed to the disease. This disease had a serious psychological effect on its victims and it was established that such effects persisted for long periods after the disease had been cured.

Several studies conducted a month after patients had been discharged revealed that thirteen to thirty two percent of them were suffering from moderate to severe anxiety and that eighteen to twenty six percent had moderate to severe depression. Another four percent were found to be suffering from Post Traumatic Stress Disorder or PTSD (Lee). The spread of SARS had a number of economic, political and sociological ramifications, due to extreme demands made on the countries, in which this disease was prevalent, by the WHO.

Some of these demands were related to a curtailment if not the rescission of economic activities like trade, tourism, and investment. Despite SARS occurring mainly in Asia, its effects were experienced in almost every major market across the world. This epidemic brought about a tremendous increase in medical expenditure and travel. In addition consumer confidence and investment reached their nadir (Political Influences on the Response to SARS and Economic Impacts of the Disease).