The History of SARS

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SARS
Introduction
Severe Acute Respiratory Syndrome (SARS) is a respiratory condition that originates from the zoonotic disease. Among the first symptoms of the disease are flu, fever,  HYPERLINK "http://en.wikipedia.org/wiki/Lethargy"
lethargy symptoms,  HYPERLINK "http://en.wikipedia.org/wiki/Myalgia"
myalgia, sore throat, cough and other  HYPERLINK "http://en.wikipedia.org/wiki/Nonspecific_symptom"
nonspecific symptoms. High fever and influenza are the only symptoms that are common to most patients. The fever exceeds 38 °C (100 °F). Shortness of the breath may also occur later. Another initial symptom is influenza. The condition was first recognized in 2003. An infection with the SARS causing virus may result to respiratory distress or severe breathing problems and in other times, death. The World Health Organization first identified the disease in 2003. The first SARS case was noted in a 48-year-old man who had travelled from the Guangdong province in China, through Hong Kong, Hanoi, and Vietnam. Both the old man and the health practitioner who had diagnosed the illness died from the condition ( HYPERLINK "/search?q=au%3AAbraham%2C+Thomas%2C&qt=hot_author"
Abraham, 2005, 4).
The first clue of the outbreak was in 27th November 2002 when the Global Public Health Intelligence Network (GPHIN) in Canada, an electronic warning system, which is part of the World Health Organization’s Outbreak and Alert Response Network (GOARN), collected reports of a “flu” like outbreak in China. This report was obtained through its Internet Media Monitoring and Analysis, and sent to the World Health Organization. While the GPHIN capacity had been gradually upgraded to enable Arabic Chinese, French, English, Spanish and Russian translation, the system was initially limited to English and French in presentation of this information. Therefore, while the first reports of the strange outbreak was in China, there was no English report until 21st January 2003 ( HYPERLINK "/search?q=au%3ADuffin%2C+Jacalyn.&qt=hot_author"
Duffin, 2006. 15).
The pandemic was significantly controlled by the affected governments in collaboration with WHO in 2003. During that year, airline passengers in affected countries were thoroughly screened at the particular airports. However, in 2004, another SARS outbreak was again reported in China. Unlike the first one, this one was not caused by human interactions, but from the contact of a laboratory virus sample (Huang, 2011, 23). Despite intense measures taken by governments and world health institutions, the disease remains to be present in animals and human beings because of its ability to mutate. Currently, the disease is spreading at a faster rate and infecting many people in almost all parts of the world.
SARS as a Zoonotic disease
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Zoonotic diseases are contagious ailments that are transmitted by animals and human beings. The main causes for these types of diseases are parasites, viruses and fungi. Either animals or insects are carriers of these diseases. Examples may include dengue, anthrax, Ebola, SARS, Lyme disease, Escherichia coli infection, Plague, Malaria, Rocky Mountain spotted fever, West Nile virus infection, and salmonellosis.
The history of Zoonotic disease is long. For example, the bible and ancient Greeks mentions the plague as a form of contagious disease. Today, there are high numbers of Zoonotic diseases that are existing in the world. SARS is among the most notorious of Zoonic diseases in the world today. In addition to other diseases we just mentioned, there are also Lyme disease, ringworms, and many other diseases that are threatening humanity. A zoonotic disease is risky to any human exposed to an infected individual, animal or disease vector. A vector refers to a disease career which transmits the disease from an infected animal to unaffected one. Some of the more risk victims are small children and infants. These groups of people are risky because of the immaturity of their immune systems and poor hygiene associated with them. Other groups of vulnerable people are pregnant women and the elderly. This is because their immune system is more susceptible with more added fetal hazards. The elderly are also immune-compromised individuals and include those with Aids, cancer and health care practitioners.
SARS is one of the zoonotic pathogens, which are transmitted to the human population by another human career, or an intermediate host such as the palm civet. In preventing the development of SARS-CoV virus and ensuing transmission into human populations, heterologous disease models have been incorporated in testing the efficiency of therapies and vaccines on human and Zoonic isolates. (Isolates are SARS careers; there are human and Zoonic/animal careers).  HYPERLINK "/pubmed/?term=Rockx B%5Bauth%5D"
Rockx and  HYPERLINK "/pubmed/?term=Feldmann F%5Bauth%5D"
Feldmann (2011), show that the zoonotic SARS-CoV strains (this is a type of virus) infect the cynomolgus macaques, and results in histopathological and radiological changes that are noted in mild human cases. Viral replications are higher in animals that are infected with a human phase isolate that comes later in relation to a Zoonotic isolate. There are significant variations in the number of host genes which are differentially regulated. The major functions and pathways were found to be similar and appear in the time of infection with the majority of genes that related to interferon signaling pathways.
SARS-CoV is a zoonotic pathogen that emanated from bats and either directly penetrated into the human population or recycled through raccoon dogs or civets as intermediate hosts. Old age was related significantly with increased SARS-related pathogens and deaths because of the rapid progression in the respiratory compromise. Based on epidemiological research, SARS-CoV epidemic is characterized through different phases. These include the early phase, the Zoonotic phase, middle and the late phase. The Zoonic phase is in turn characterized by isolated strains from the raccoon dogs and palm civets that thrive in animal markets. The early phase was featured by various independent human cases, which are mostly related to Zoonotic transmission. The middle phase is characterized by initial human-to-human transmission. The late phase on the other hand, is characterized by effective human-to-human transmission as well as the widespread global transmission in over 30 countries.
The SARS-CoV spike (S) glycoprotein has been noted as being the main mediator for virus penetration and host range by binding it to its receptor angiotensin 1, which is converted to enzyme 2 (ACE-2). A high rate of mutation of the S glycoprotein was noted between the various isolates from both the humans, and animals and several changes to amino acids. These were being identified as being critical for the transition and transmission among human beings. Presently, there are various animal models for SARS CoV that are in extant. These include hamsters, mice, non-human primates, and ferrets. Whereas these models have been employed for studies in pathogenesis and vaccine development, majority of such studies were focused on isolates from the late stage to the eventual outbreak. The heterogonous challenge of mice after vaccination against the late phase S glycoprotein provided only partial protection.
Both the early and late human phase viruses replicated to high level in human ciliated airway epithelial cultures especially where the Zoonotic isolate did not exist. Interestingly, the early zoonic and human phase isolates are lethal in older mouse models which results in extreme lung infection which progresses in an early organizing phase of ARDS and death (Rockx, 2007, 7423).
Before the emergence of SARS, coronavirus had been detected in both livestock and human populations. However, all the previously known human coronaviruses only resulted to mild respiratory symptoms and have never been related with severe human disease. This is actually what has made the SARS disease unique. These aspects also made the search for the particular cause of the disease to be a complicated affair. It is noteworthy that coronaviruses had not been extensively studied before, and its origin was even more complex to establish. Initial evidence indicated that SARS...