Coronavirus, Coronavirus Disease 2019 (COVID-19 or 2019-nCoV)

Table of contents

Coronavirus disease 2019 (COVID-19)

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What is Coronavirus?

A SARS-CoV-2 virion (a single virus particle) is about 80 nanometers in diameter.
The pathogen is a member of the coronavirus family, which includes the viruses responsible for SARS & MERS infections.
It is an RNA virus with ribonucleic acid (RNA) as its genetic material instead of DNA.
That means the virus blends with its host’s DNA & can mutate rapidly.
It’s covered by spiky protrusions like on a crown (hence the name Corona), which are in turn enveloped in a layer of fat (the reason soap does a good job of destroying the virus).

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COVID-19 is an infectious Zoonotic Disease, caused by a newly discovered SARS–CoV–2 coronavirus.
SARS–CoV–2 can trigger what doctors call a respiratory tract infection.
Disease- nCoV- n=novel meaning new, Co =corona, V=Virus
Disease- Covid 19- Co=corona, Vi=virus, d=disease,19=2019
Virus – SARS-CoV-2- meaning-severe acute respiratory syndrome coronavirus 2.
Viruses, & the diseases they cause, often have different names. E.g. HIV is the virus that causes AIDS.
Covid-19, like SARS, MERS, AIDS, & Ebola, is a zoonotic disease—it jumped from another species to humans.
This probably happened in late 2019 in Wuhan, China.
Scientists believe bats are the likeliest reservoir.
It might have jumped from bats to pangolins & then to humans.
Symptoms include dry cough, fever, fatigue, muscle aches & acute breathing difficulty.
The incubation period for the virus can last from 10 to 14 days.
The infection can cause pneumonia, respiratory distress, kidney failure & in some cases, in which immunity is weak, even death.
As of now, there is no vaccine against coronavirus infection. There is also no cure for the 2019-nCoV.

Zoonotic diseases (also known as zoonoses) are caused by germs that spread between animals & people.
Zoonoses may be bacterial, viral, or parasitic, or may involve unconventional agents.
As well as being a public health problem, many of the major zoonotic diseases prevent the efficient production of food of animal origin & create obstacles to international trade in animal products.

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So far, there are four known disease-causing coronaviruses, among which the best known are the SARS coronavirus & the Middle East Respiratory Syndrome (MERS) coronavirus.
Severe Acute Respiratory Syndrome (SARS) outbreak in China in 2002-03 killed nearly 800 people.
The SARS coronavirus is thought to be an animal virus from a yet-uncertain animal reservoir, perhaps bats, that spread to other animals & first infected humans in the Guangdong province of China in 2002.
The MERS coronavirus was passed on from camels to humans in Saudi Arabia in 2012.

The virus’s protein spikes attach to a protein on the surface of host cells, called ACE2.
ACE2 acts as the receptor for the SARS-CoV-2 virus and allows it to infect the cell.
Normally, ACE2 plays a role in regulating blood pressure.

The virus enters the body through the nose, mouth or eyes, then attaches to cells in the airway that produce a protein called ACE2.

The virus infects the cell by fusing its oily membrane with the membrane of the cell.
Once inside, the coronavirus releases a snippet of genetic material called RNA.

The virus’s genome is less than 30,000 genetic “letters” long (Ours is over 3 billion).
The infected cell reads the RNA & begins making proteins that will keep the immune system at bay & help assemble new copies of the virus.
Antibiotics kill bacteria & do not work against viruses.
Researchers are testing antiviral drugs that might disrupt viral proteins & stop the infection.

As the infection progresses, the machinery of the cell begins to churn out new spikes & other proteins that will form more copies of the coronavirus.

Each infected cell can release millions of copies of the virus before the cell finally breaks down & dies.
The viruses may infect nearby cells, or end up in droplets that escape the lungs

Most Covid-19 infections cause a fever as the immune system fights to clear the virus.
In severe cases, the immune system can overreact & start attacking lung cells.
The lungs become obstructed with fluid & dying cells, making it difficult to breathe.
A small percentage of infections can lead to acute respiratory distress syndrome, & possibly death.

Coughing & sneezing can expel virus-laden droplets onto nearby people & surfaces, where the virus can remain infectious for several hours to several days.

Stage 1 | Imported Cases: These are those who have travelled to virus-hit foreign countries & have come back to India.
Stage 2 | Local Transmission: These are those cases who have come in contact with patients who have a travel history.
Stage 3 | Community Transmission: Community transmission is when a patient not exposed to any infected person or one who has travelled to any of the affected countries tests positive. Large areas get affected when community transmission takes place.
Stage 4 | Epidemic: This is the last & the worst stage where the disease takes the shape of an epidemic with no clear endpoint like it did in China.

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A vertically transmitted infection is an infection caused by pathogens (such as bacteria & viruses) that use mother–to–child transmission.
It is transmitted directly from the mother to an embryo, fetus, or baby during pregnancy or childbirth.

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Case Fatality Rate (CRF) measures the severity of a particular disease by defining the total number of deaths as a proportion of reported cases of a specific disease at a specific time.
CFR is presented as a percentage (0%–100%) or a ratio (between 0–1) & measures the number of confirmed deaths among the number of confirmed diagnosed cases of a particular disease at a given time.