Running Head: LITERATURE REVIEW 1
LITERATURE REVIEW 3
The main objective of this literature review is to report about SARS, MERS, and SARS-CoV2. It will focus on the origin of the three viruses and the respiratory illnesses they cause. It will also cover the effects they had on a personal, national, and economic level. It will also include the mode of transmission from one human to another and the necessary measures that were taken and ones that should be taken to control the viruses. The most recent of the viruses is SARS-CoV2, which currently affects the whole globe where no cure has been found (Saboowala, 2020).
CAUSE OF SARS
Severe Acute Respiratory Syndrome (SARS), also known as SARS coronavirus (SARS-CoV), was first identified in 2003. It is not yet proven from which animal it came from, but it as an animal virus thought to be from bats. Strains of coronavirus are what causes Severe Acute Respiratory Syndrome. It is the same family of viruses that cause the common cold. It spread to other animals but mostly affected the civet cats. The first human infection of SARS was in the year 2003 in Guangdong province, Southern China. This illness was transmitted to more than 24 countries in Asia, Europe, North America, and South America before the pandemic was contained SARS. The area is considered the potential for the re-emergence of SARS-CoV. It spread to other areas of Toronto in Canada, Hong Kong, Viet Nam, and Chinese Taipei. There have never been any cases of SARS since 2004 that have been reported in any country in the world. However, in July 2003, the virus re-appeared three to four times in Singapore and Chinese Taipei through laboratory accidents (Cavanagh, 2008).
TRANSMISSION OF THE VIRUS
SAR-CoV transmission is basically from person to person. It was observed that it mainly occurred in the second week of the illness. This is the peak of excretion of the virus in the patient’s stool and his or her respiratory secretions. This time is when severe disease cases start deteriorating clinically. Due to the absence of proper infection control precautions, most human-to-human infections mostly was in hospitals. Just as all respiratory illness spread through respiratory droplets by entering the air, SARS is also transmitted the same way. The transmission was mostly through close and prolonged contact with an infected person and droplets from infected persons. Some health workers were also infected with the virus in their line of duty. The virus can also be spread through contacting contaminated objects like telephones, elevator buttons, or doorknobs. Generally, people who come in close and direct contact with people who are infected are at a higher risk of contracting the virus. SARS spreads very quickly in the interconnected and mobile world. There were no reported cases of laboratory workers being infected with the virus during diagnostic assays. However, caution should be taken when handling the specimen to be tested. Clinical and laboratory staff should have frequent communication to minimize their exposure to the virus when handling samples from infected patients. These specimens should be labeled, and laboratory staff should be alerted for proper specimen handling. (Davis & Siu, 2006).
SYMPTOMS AND COMPLICATIONS OF SARS
There were several symptoms of SARS-CoV though there were no symptoms that were proven to be specific for the diagnosis of the disease. The main symptoms observed were fever, headache, shivering, diarrhea, malaise, and myalgia. Fever was the most reported symptom but was sometimes absent on first measurements, often in the aging people and in immunosuppressed patients. In the first and second week of illness, dry coughs, diarrhea, and shortness of breath were mostly experienced. When the disease developed to severe stages, which it rapidly evolved, intensive care was required. It is a severe disease that can lead to death. Anyone experiencing symptoms of respiratory disease is always advised to seek medical attention from a doctor immediately. The virus also causes some complications to the patient. Patients may develop pneumonia and problems in breathing whose severity might increase to the point that mechanical respirators be used on the patients. To some patients, the virus might be fatal, causing respiratory failure. It may also cause liver failure or heart failure. People who are 60 years and above and with pre-existing conditions are the most vulnerable to SARS and of these complications. (Kleinman & Watson, 2006).
EFFECTS OF SARS VIRUS
Psychologically, SARS virus cases resulted in emotional sadness. The patients stayed in the hospital for long, and they could not be allowed to see their families avoid close contact with them. This caused some mental disorder. Psychological counseling was necessary for patients. The virus also caused a largely impacted society more so in China. It resulted in a lot of tension in society. Accurate information was not given to the public creating false information to spread through social media, mobile short messages, and word of mouth. These false rumors caused social panic and resulted in people in Guangdong buying the wrong drugs. SARS not only affected the physical and mental health of people; it also affected the economy. Asian states lost approximately 12-18 billion United States dollars as the virus greatly affected tourism and industries. Families were forced to reduce their expenses for food, travel, clothes, and entertainment, which negatively affected their country’s economy (Ramen, 2005).
TREATMENT AND PRECAUTION STRATEGIES
When SARS-CoV first appeared, it caught the world by surprise, and randomized clinical trials in finding the treatment were not possible. Due to the collaboration between countries, health experts were able to contain the spread of the virus. These efforts are also the reason why there has never been any case of SARS since 2004. In the early stages of the pandemic, a combination of corticosteroids and ribavirin was used as a treatment, and after testing the first few patients, it gave some excellent results. Some other reports showed that ribavirin was highly toxic and did not have a vitro antiviral effect on the SARS-coronavirus. Up to date, there has never been any existing treatment of SARS-CoV. Some safety guideline that is recommended and stated as follows; washing hands using hot water and soap or using a hand cleanser that has 60% alcohol content. People were also advised to use disposable gloves when coming into contact with another person’s feces or body fluids. However, the gloves should have been immediately disposed of and thoroughly wash your hands. People were also directed to wear a surgical mask when in the same room with a person infected with SARS or further even use eyeglasses, which offers additional protection. People were also advised to use warm water and soap to clean utensils, clothes, and beddings of an infected person to prevent further spread of the virus. It was also advised to use household disinfectants to wash surfaces that might have been contaminated by body fluids such as mucus, sweat, saliva, stool, vomit, or urine from an infected person. When cleaning the surfaces, one was supposed to wear disposable gloves and properly dispose of them after use. Parents were also supposed to keep their children at home and not allows them to go to school in case they showed fever-like or respiratory infection symptoms. Standard laboratory practices should be followed by clinical laboratories that perform routine urinary and clinical studies and microbiology laboratories who perform diagnostic tests on urine, serum, or blood specimen of a person infected with SARS. Biosafety Level work practices should be followed by pathologists and microbiologists performing tests on respiratory or stool sample from a patient infected with SARS. In the laboratory, personal protective gear like eyeglasses, gloves, gowns, and masks should be used when handling these specimens or when carrying out procedures that cannot be conducted in a BSC (Serradell, 2009).
Middle East Respiratory Syndrome Coronavirus (MER-CoV) was reported first in Saudi Arabia in 2012. It causes a severe and fatal acute respiratory disease similar to the illness caused by Severe Acute Respiratory Syndrome coronavirus. The majority of the illness reports were either from the Middle East or close contacts of an infected person from the Middle East. It caused sporadic infections, family members’ infections, and health workers’ infections. Most of the patients with MERS-CoV had medically comorbid conditions. From laboratory tests, most cases raised aspartate aminotransferase and lactate dehydrogenase concentration, which in association with lymphopenia and thrombocytopenia. The source of virus in sporadic infected patients is not known, but there are speculations that it might have originated from bats and transmitted to dromedary camels. About 35% of patients reported with MERS died. MERS is a member of Coronaviridae, which is of the order Nidovirales. Just like the rest of the viruses that cause respiratory illnesses, MERS is a single-stranded large positive sensed RNA virus. It easily adapts to a new environment and enhances transmission to cross-species because of the ability to encode a large population of proteins.
MERS contains four main proteins structure, namely; nucleocapsid (N) protein, spike (S) protein, membrane (M) protein, and envelope (E) protein. The S protein is made up of S1 and S2 subunits and is a transmembrane glycoprotein of type I found on the virus surface as a trimer. Its primary function is to bide, fuse, and enter into the cells of the host. The S1 subunit binds to the dipeptidyl peptidase, which is the cellular receptor of the host through the receptor-binding domain. The S2 subunit is made up of two locations. Namely, heptad repeats 1 and 2. The two regions become a six-helix bundle by rearranging to enhance the fusion of the membrane. The E and M proteins found in the viral layer ae used for budding, viral assembly, and intercellular trafficking.
MERS virus gains entry to the host cells by fixing its S protein to the DPP4 receptor of the host cell. DPP4 is not commonly found in the cavity in the nasal region and the upper airway epithelial cells. Still, it is densely populated on the epithelial cells found on the distal airway and in lung alveoli in type I and II pneumocytes. DPP4 is also found in large amounts in on epithelial of several other tissues and organs like bone marrow, intestines, liver, thymus, and kidney. Thus, the MERS virus could be widely disseminated all over the body. Representation of patients affected with MERS in a clinical format is from asymptomatic, which is also referred to as upper mild respiratory illness to rapidly developing pneumonia, septic shock, failure of the respiratory system, multiorgan failure, and acute respiratory distress syndrome with fatal outcomes. It is impossible to differentiate asymptomatic patients from those with mild disease. Many people develop the mild disease, while others remain asymptomatic. (Blackwelder, 2012).
SIGNS AND COMPLICATIONS OF MERS-COV
Most of the patients diagnosed with MERS-CoV had a severe respiratory illness where they experienced symptoms such as shortness in breathing, coughing, and fever. Some patients had diarrhea and vomitingmost infected experienced more severe complications like kidney failure and pneumonia after some time. Most of the reported deaths were from people who had a pre-existing disease, which made their immune system weak. Others had underlying conditions that had not been discovered before the infection. Medical conditions generally weaken the immune system and make people vulnerable to illnesses. Pre-existing diseases that were common to people who got infected with MERS were conditions such as chronic kidney disease, chronic lung disease, cancer, chronic heart disease, and diabetes. Some patients were asymptomatic, while others had mild symptoms. The symptoms start manifesting 5 to 6 days after exposure but mostly take 2 to 14. Some patients may experience neuromuscular manifestations such as weakness, hypersomnolence extremities tingling, which is similar to sensory neuropathy that is related to the virus. (Gideon Informatics & Berger, 2020).
TRANSMISSION OF MERS
MERS is a zoonotic virus meaning it is mostly transmitted between animals and human beings. The virus spread from contacts of secretions from the respiratory system of an infected person through activities like coughing. People contracted this virus through close contact with a patient already infected. People infected transmitted it in hospitals. All cases reported were traced to people living in the Arabian Peninsula or those who had traveled there recently. The most significant reported number of circumstances outside the Arabian Peninsula was in Korea in 2015. It was spread from people who had traveled back to the country from the Arabian Peninsula. Twenty-seven states have reported MERS since 2012. These countries include; Yemen, Turkey, Thailand, United Kingdom, Tunisia, United States of America, Austria, United Arab Emirates, Republic of Korea, the Netherlands, Kingdom of Saudi Arabia, Malaysia, Qatar, Philippines, Oman, Greece, Algeria, Lebanon, France, Bahrain, Egypt, Islamic Republic of Iran and China. About 80% of the infections were from Saudi Arabia. (Hui et al., 2016).
EFFECTS OF MERS
Health care workers who were performing MERS-related tasks were reported to be at a high risk of experiencing post-traumatic stress disorder symptoms. A psychiatric and counselor’s intervention was necessary. MERS also reduced tourism revenue in the affected areas where domestic and non-citizen visits mainly decreased. The demand for food, beverages, clothes, and transport also reduced (Li & Du, 2019).
There exists no vaccine that can protect people from MERS. There is also no developed antiviral treatment for MERS-CoV illness. MERS patients mostly receive medical care to relieve them of the symptoms. Patients with severe infections receive care to support vital body organs for them to function normally. Efforts to develop a treatment for MERS are gradually increasing are limited continuously in the scope and the advanced stages of the virus. Some medications that are based on antibodies that neutralize naturally, such as hyperimmune globulin, have proven to be somehow effective and in mortality reduction of infections such as MERS-CoV. This, however, depends on faster identification of diseases and close contacts and immediate application of the treatment for maximum effect. Generally, people visiting markets farms and dromedary camels and other animals are being advised to enhance hygiene measures such as frequent hand washing before and after having contact with animals and should altogether avoid coming into contact with sick animalsother places where. Consumption of raw animal products such as meat and milk were discouraged because they are very likely to be infected with disease-causing organisms in human beings. However, appropriately processed animal products through pasteurization or cooking could be consumed but with care by avoiding contact with raw foods. As it is known that camel milk and meat are very nutritious, they should only be destroyed cooking, pasteurization, or other treatments through heat. People with pre-existing medical conditions such as diabetes, lung disease, or heart disease are a higher risk of contracting MERS; hence should avoid coming into contact with camels or consuming uncooked milk or meat from camels.
Healthcare givers contracted the disease from patients before the disease was diagnosed. This is because it is impossible to identify infected people before testing symptoms are not specific. For this reason, healthcare workers were educated and trained in the prevention of infections. To achieve long protection against other re-infection of the virus, accurately coordinated innate and adaptive T-cells and B-cells is crucial. Patients who are infected with MERS with immune responses have an extension of cytokine secretion period. Patients who showed severe symptoms in the acute phase of the virus were examined, and robust virus CD8 T-cell was identified. The CD4 T-cells and antibodies were found to appear at later stages of the disease. Some survivors of MERS were examined, and it was found that the responses of MERS virus-specific antibodies were transient and lower in patients who had mild disease compared to those with a severe illness whose MERS virus-specific antibodies responded for at least two years. In MERS survivors, T-cells responded for at least two years. The nature of the antibodies of being transitory in patients with mild disease and the T-cell stable response showed that when both of them are induced, optimal long-term protection will be achieved. The accuracy of prevalence studies will be enhanced through this measurement (World Health Organization, 2015).
SARS-CoV2 is the virus that leads to coronavirus disease 2019 (COVID-19) and is the first report in Wuhan, Hubei province in China, in November 2019. It then spread to countries as far as the United States of America and the Philippines and every part of the world. It is described as the successor to SARS-CoV1. It is believed that the virus originated from bats. It then jumped the species barriers through an intermediate animal host to human beings. The intermediate host might have been a domestic animal used as food by human beings. This wild animal has been domesticated or generally a domestic animal that is yet to be identified.
Generally, SARS-CoV2 has been proven to be stable in frozen areas because the other related coronaviruses have survived for up to two years at -20oC. This virus is susceptible to a cooking temperature, which is about 70oC; hence eating raw food is discouraged. It is also vulnerable to cleaning products and disinfectants (Hohenheim, 2020). The structure of SARS-CoV2 is as shown below:
SIGNS AND COMPLICATIONS CAUSED BY SARS-COV2
In the early stages, people infected with SARS-CoV2 experience mild respiratory illnesses. However, some people affected by COVID-19 are asymptomatic. The most common symptoms that patients infected with COVID-19 have shown are; fever that gradually increases the body temperature, coughing which becomes more severe over time. Patients also experience sore throats, fatigue, and shortness of breath. Some other symptoms that are not very common are muscle aches, continuous shaking, and chills. Patients with weakened immune systems may develop severe conditions like pneumonia or bronchitis. The incubation period for COVID-19 is approximately 5-6 days. COVID-19 can cause a complication that is a type of pneumonia referred to as NCIP pneumonia (2019 novel corona virus-infected) (Mears, 2020).
TRANSMISSION OF SARS-COV2
Since COVID-19 is a respiratory disease, it can be transmitted through respiratory droplets. The transmission takes place when an individual comes into close contact with the respiratory droplets of an infected person when an infected person sneezes or coughs. It occurs through direct contact with an infected person and indirect contact from surfaces or objects used by an infected person. The virus may also lead to infections hence may be present in feces. Healthcare workers have also been infected with the disease through contacts from infected patients. Most of the affected people are adults though children are also at a high risk of contracting the virus. Travelers from countries affected with the disease, and people who come into close contact with the returnees might also contract the disease.
People who are 65 years old and older than that are most likely to have severe symptoms in case of infections. Those with medical conditions like diabetes, lung cancer, or heart disease are also vulnerable to this disease. People with HIV are also at a higher risk of contracting the disease because of their weak immune system. However, pregnant women cannot transmit the virus to their child during pregnancy, but the child might contract it after birth (Miller & Pearson, 2020).
EFFECTS OF SARS-COV2
COVID-19 has caused fear of the worlds economy recessing and other economic crises. The travel restrictions and social distancing has decreased the workforce across all countries and has led to many people losing their jobs. The demand for manufactured products has dramatically reduced, leading to some industries collapsing. However, the need for medical supplies has increased. There has also been a rapid increase in food demand, which is a threat to the world’s food security because less food is produced due to the pandemic. It has also affected our education because it has led to the closure of education facilities. It has also caused some psychological effects due to fear, financial constraints, unemployment, and social-distancing (Paul Kilgore, 2020).
Currently, there exists no specific treatment or vaccine approved to treat COVID-19, although some scientists are currently working hard to develop a vaccine. For now, treatment is focused on symptom management. The best-recommended way of preventing the transmission of COVID-19 is by avoiding contact with infected people. It is also advised that one should maintain proper hygiene and practice social distancing. One should frequently wash his or her hands using running water and soap for up to 20 seconds. One can also use alcohol-based hand cleansers. People must also avoid touching faces, eyes, mouth, or nose using dirty hands.
People should also stay at home if they feel sick or experience any flu-like symptoms to avoid spreading the disease in case they contracted it. One should also cover their mouth when coughing or sneezing and should cough into a disposable tissue and immediately dispose of the tissue appropriately or sneeze into your elbow. One should also stay at least 2 meters away from people in public places. In public settings, it is also advisable to always wear a face mask that covers your nose and mouth. The mask blocks respiratory droplets from infected people to get into your system (Saboowala, 2020).
The literature generally discusses three viruses, which are SARS, MERS, and the most recent SARS-CoV2. The three viruses cause acute respiratory illnesses, which are transmitted through respiratory droplets of an infected person. Severe Acute Respiratory Syndrome (SARS), also referred to as SARS coronavirus (SARS-CoV), was reported first in 2003. Middle East Respiratory Syndrome Coronavirus (MER-CoV) was published first in Saudi Arabia in 2012. SARS-CoV2 is the virus that leads to coronavirus disease 2019 (COVID-19) and is the first report in Wuhan, Hubei province in China, in November 2019. The main symptoms observed in SARS patients were fever, headache, shivering, diarrhea, malaise, and myalgia. The temperature was the most reported symptom but was sometimes absent on first measurements, often in the aging people and in immunosuppressed patients.
Patients diagnosed with MERS-CoV had a severe respiratory illness where they experienced symptoms such as shortness in breathing, coughing, and fever. Some patients had diarrhea and vomitingmost infected experienced more severe complications like kidney failure and pneumonia after some time. Most of the reported deaths were from people who had a pre-existing disease, which made their immune system weak. Patients infected with COVID-19 had symptoms such as a fever that gradually increases the body temperature, coughing, which becomes more severe over time. Patients also experience sore throats, fatigue, and shortness of breath. With the tree viruses, some patients were asymptomatic.
SARS resulted in a lot of tension in society. Correct information was not given to the public causing false information to spread through social media, mobile short messages, and word of mouth. These false rumors caused social panic and resulted in people in Guangdong buying the wrong drugs. MERS reduced tourism revenue in the affected areas where domestic and non-citizen visits mainly decreased. The demand for food, beverages, clothes, and transport also reduced. SARS-CoV2 has also caused travel restrictions and social distancing, which has reduced the workforce across all countries and has led to many people losing their jobs. The demand for manufactured products has dramatically decreased, leading to some industries collapsing. However, the need for medical supplies has increased, which might lead to shortages. All three viruses had adverse effects on the affected areas.
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