Since the evolution of living species, human beings have been vulnerable to several bacteria, viruses, and other pathological microorganisms. One of the viruses that are the cause of the recent havoc in the world is the coronavirus or COVID-19. This large group of viruses target mammals and birds, affecting them with varying symptoms from flu to pneumonia.
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According to science, there are hundreds of corona viruses in the world. Among them, only seven are known to affect human beings. However, not all of them are deadly. Four of the corona viruses cause mild flu and cold-like symptoms. The other three pose more serious threats to the health of the infected person.
The name “corona” means crown in Latin. The scientists named coronaviruses after their appearance. The surface of these viruses is covered with spiky projections – resembling a crown. (Vandergriendt, 2020)
Background of Coronavirus Outbreaks
Initially, when the coronaviruses were being investigated, they were not considered as pathogenic- as they are now. However, things changed when a mysterious strain of coronavirus hit the Guangdong province of China in 2002 and 2003. The outbreak of this strain of coronavirus – known as SARS-CoV (severe acute respiratory syndrome) transformed the reputation of these viruses, as it affected billions of people around the world and caused more than a million deaths. After ten years of SARS, another coronavirus – Middle East Respiratory Syndrome coronavirus (MERS – CoV) attacked the Middle Eastern countries. In 2019, another strain of coronavirus – SARS – CoV 2 emerged in Wuhan, China.
The difference between SARS and MERS is the way they attack the cells in the body. The receptor that SARS uses is angiotensin-converting enzyme 2 (ACE2). The target of this strain of coronavirus are ciliated epithelial bronchial cells and type 2 pneumocytes. On the other hand, MERS-CoV makes use of dipeptidyl peptidase 4 (DPP4) as a receptor and attacks un-ciliated bronchial epithelial cells and type 2 pneumocytes.
The origin of both of these coronaviruses – SARS and MERS was traced back to bats. However, in the case of these two strains of viruses, human beings got infected by getting in contact with it through civets and dromedary camels. (Cui, 2019, 181-192)
The case with Covid-19 is different, as it originated from bats in the wet markets of Wuhan, China.
Corona CVruses Found in Human Beings
Until now, seven human coronaviruses (HCoVs) have been identified in the laboratories. The four of them are known as less high-risk and cause typical symptoms of flu and cold. It is to be noted that those people who are already battling with life-threatening diseases, senior citizens, and infants might be left with severe after-effects, even from the not-so risky strains of coronaviruses. (UK Research and Innovation, 2020)
. The four common coronaviruses in human beings are:
- HKU1 (Vandergriendt, 2020)
However, the other three that include SARS, MERS, and Covid-19, are the deadlier ones as they are responsible for causing symptoms like breathlessness, excruciating body pain, dry flu/cough, and pneumonia. People contracting SARS, MERS, and Covid-19 viruses are at risk of losing the battle of life as the end stage of these strains of coronaviruses is a drastic decrease in the oxygen concentration leading to death. (UK Research and Innovation, 2020)
The following are some facts about the deadly coronaviruses found in human beings
The SARS-CoV is known to cause severe acute respiratory syndrome in human beings. According to the findings recorded by the World Health Organization WHO, the first human case of SARS coronavirus surfaced up in southern China in November 2002. The animals responsible for the spread of SARS-CoV were found to be bats. From them, the virus transferred from one animal to another.
The pandemic of 2002-2003 affected thousands of people all around the world. The statistics show that more than 8000 people in about 26 countries got infected by SARS all around the world. The death toll was recorded to be 774. This worldwide outbreak was contained in mid-2003. It was only possible because of the strict implementation of virus control measures such as social distancing, isolation, and quarantine.
Now, there are rare cases of SARS-CoV after the 2003 pandemic. Only a small number of infections have come into the light due to laboratory accidents. As of now, there are no reported cases of SARS due to laboratory mishaps.
The MERS-CoV is the second strain of coronavirus that shocked scientists with its pathogenic abilities. It is known to cause Middle East Respiratory Syndrome (MERS). According to WHO, the initial emergence of this coronavirus happened in Saudi Arabia in 2012. However, after a detailed investigation, it was later announced that the first case of MERS probably occurred in Jordan.
Humans get infected by MERS coronavirus through close contact with camels that are already contaminated with the virus. However, the spread of the disease was mostly due to person-to-person infection. From the year 2012, the authorities propose that 2,400 cases have been reported in about 27 countries around the world. Unfortunately, the central point of attack of MERS has been Saudi Arabia.
In 2015, MERS penetrated South Korea and infected 186 people. Among them, 36 patients lost the fight against it. According to CDC studies, a traveller from the Middle East spread the virus in South Korea. In 2019 alone, the European Center for Disease Prevention and Control (ECDPC) recorded 200 cases of MERS-CoV globally.
3) SARS-CoV 2
This strain of coronavirus is the latest and also the most damaging one yet. SARS-CoV is the one causing Covid-19 around hundred of countries in the world. The first case of Covid-19 emerged in Wuhan, China, after the doctors noticed an uprise in pneumonia cases with no known cause. The virus originated from a wet market in Wuhan. In the case of Covid-19, bats are the animals that carried the virus in the first place. However, its exact source is still under observation. (Vandergriendt, 2020)
As of now, around 67.3 millions of people have contracted Covid-19, and 1.54 million deaths have been recorded by WHO.
The world is still recovering from the loss of life, economy, and resources caused by the Covid-19 pandemic. Health officials are working day and night to come up with a cure so that the human population is rid of this deadly illness.
Cui, J. (2019). Origin and evolution of pathogenic coronaviruses. Nature Reviews, 17(3), 181-192. https://europepmc.org/article/MED/30531947
UK Research and Innovation. (2020, March 25). What is coronavirus? The different types of coronaviruses. Coronavirus explained. https://coronavirusexplained.ukri.org/en/article/cad0003/
Vandergriendt, C. (2020, March 31). What Is a Coronavirus? Healthline. https://www.healthline.com/health/coronavirus-types