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

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).

Link– Source & Credits

2019-nCoV (COVID-19)

  • 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 Disease

  • 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.

Link– Source & Credits

Previous Coronavirus Outbreaks

  • 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.

How does Coronavirus get into Human Cells?

  • 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.
Entering a Vulnerable Cell
  • The virus enters the body through the nose, mouth or eyes, then attaches to cells in the airway that produce a protein called ACE2.
Releasing Viral RNA
  • 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.
Hijacking the Cell
  • 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.
Making Viral Proteins
  • 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.
Assembling New Copies
  • New copies of the virus are assembled & carried to the outer edges of the cell.
Spreading the Infection
  • 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
Immune Response
  • 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.
Leaving the Body
  • Coughing & sneezing can expel virus-laden droplets onto nearby people & surfaces, where the virus can remain infectious for several hours to several days.

Stages of Coronavirus Transmission

  • 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.

Link– Source & Credits

What is Vertical Transmitted Infection?

  • 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.

Difference between Outbreak, Endemic, Epidemic & Pandemic

Link- Source & Credits

What is Case Fatality Rate (CFR)

  • 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.
CFR of Common Diseases

Specific CFRs of particular diseases if left untreated or unvaccinated for include:

  • Bubonic Plague – 60%
  • Spanish Flu (1918) – 2.5%
  • Ebola – 90%
  • Naegleriasis – 99%
  • Smallpox – 95%
  • Seasonal Influenza – 0.1%
  • HIV/AIDS – 80%
  • Dengue Fever – 26%
  • Malaria – 0.3%
  • Typhoid – 10–20%
  • SARS – 9–11%
  • MERS – 34.4%
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