Coronaviruses are a large family of enveloped, non-segmented, single-stranded, positive sense RNA viruses that circulate among animals including camels, cats, and bats. Coronaviruses derive their name from their electron microscopic image, which resembles a crown. see below.
Six strains of coronavirus have infected humans, four of which are together responsible for about 1/3 of common colds. In the past two decades, there have been three global coronavirus outbreaks.
1-Severe Acute Respiratory Syndrome (SARS)
It is caused by a coronavirus termed SARS-CoV, started in 2003 in Guangdong, China, and spread to many countries in southeast Asia, North America, Europe, and South Africa. Bats are the natural hosts of SARS-CoV. The virus infected 8,069 persons and caused 774 deaths, the last known case of SARS was detected in September 2003.
2- MERS-CoV
It causes Middle Eastern Respiratory Syndrome (MERS) – emerged in Saudi Arabia. MERS is characterized by sporadic zoonotic transmission from camels and limited episodes of person-to-person transmission. The symptoms of MERS are nonspecific, but many patients develop atypical pneumonia and severe acute respiratory distress.
3-SARS-CoV-2.
On December 30, 2019, a cluster of patients with pneumonia of unknown etiology was observed in Wuhan-China and reported to the World Health Organization , China bureau in Beijing. By January 2, 2020, the full genome of a new coronavirus had been sequenced by Shi Zhengli-a coronavirus expert at the Wuhan Institute of Virology. The sequence had been published and the Chinese National Health Commission warned of its potential danger. The virus was initially referred to as (novel coronavirus 2019) (2019-nCoV) by the WHO. On February 11, 2020, was given the official name of SARS-CoV-2 by the International Committee on Taxonomy of Viruses.
How the virus evolved to become transmissible to humans is not known, but two theories predominate: either natural selection in an animal host before zoonotic transfer to humans, or natural selection in a human host after zoonotic transfer.
Risk factors for COVID-19
- 1- older age
- 2- ethnicity
- 3- male gender
- 4- diabetic patients
- 5- kidney and liver patients
- 6- cancer patients
- 7- immunosuppression
- 8- chronic lung problems
The mean duration from symptom onset to death is 18 days. Case fatality rate (CFR), which is calculated by dividing the number of deaths by the number of known cases has been reported at 6.4 percent worldwide , significantly higher in older patients. CFR almost certainly overestimates the true lethality of the virus. The number of confirmed cases usually includes only people whose symptoms were severe enough to be tested, resulting in a severity bias. Epidemiologists estimate there are five to 10 times more people with asymptomatic infections. The number of deaths may be inaccurate at the time of calculation because deaths typically occur one to two months after a person becomes infected and not all deaths are apparent at the same time. COVID-19 deaths that occur at home are underreported compared with those that occur in a hospital.
To date, there are no specific vaccines or medicines for COVID-19. Treatments are under investigation, and will be tested through clinical trials.
Self Care
If you feel sick you should rest, drink plenty of fluid, and eat nutritious food. Stay in a separate room from other family members, and use a dedicated bathroom if possible. Clean and disinfect frequently touched surfaces.
Medical treatment
Dexamethasone has been reported to decrease the mortality rate of patients with severe respiratory illness.
Remdesivir , a nucleoside prodrug that inhibits transcription of many RNA viruses, may shorten COVID-19-related hospital stays by an average of three days
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