Before December 2019, Wuhan was a city in China known for hosting the 2019 Military World Games, its remarkable architecture and the two rivers that run through it.
Then on December 31 that very year, the city hit the media umbrage as the origin of a viral Covid-19 disease that has since killed more than 28,000 people globally according to the World Health Organisation (WHO).
The novel coronavirus (2019-n-CoV), which was renamed the coronavirus disease or just Covid-19, has now become a household name for health ministries and ordinary people as it leaves behind a body count of as many as 900 in a day.
What is Covid-19?
It belongs to a family of viruses called the coronaviruses that have strains that cause deadly diseases in mammals and birds.
The virus that causes the disease — like HIV causes AIDS — is called SARS-CoV-2.
These viruses are zoonotic, meaning they originate from animals to come to people.
So far, seven of them have made this migration: four little known ones that have been implicated in causing mild flu; Middle East respiratory syndrome (MERS) and Severe Acute respiratory syndrome (SARS) that have been deadly as well as but did not spread as fast Covid-19.
SARS and MERS, known as the ‘SARS classic, are estimated to have killed more than 1,500 people since 2002.
Initially, scientists had not expected Covid-19 to claim so many lives than SARS-classic but they have been shocked at the virus’ lethal itinerary.
Dr Marianne Mureithi, acting chairperson of the Department of Medical Microbiology in the College of Health Sciences at the University of Nairobi, points to its shape.
The spikes on the body of the virus attach themselves to a protein called ACE2 in our bodies. This is where the infection begins.
Since SARS, studies have gone into the role of this protein in causing severe pulmonary infections.
ACE2 acts as an usher (receptor) these viruses. Unlike MERS and SARS, the spikes in SARS-CoV-2 remain firmly attached to the protein harder and firmly.
Also, the spikes on the virus are connected at the root in a V-Shape.
As the virus tries to get access to human cells, they separate, broken so easily by an enzyme called furin which is manufactured in many cells in our bodies.
The other two lethal viruses struggled to make this separation, making the spread far less rapid.
These activities take place in the first days of an infection. From there, the virus invades the lungs attacking two types of cells that make mucus—yes, mucus— and some that hold some hair called cilia.
Before we talk about what mucus has to do with this disease, it is worth noting that the lungs are the battle fields and that this is where a patient dies or lives.
It is in those sacs of air that the virus multiplies, overwhelms the body’s immune system and eventually annihilates the breathing system, at least according to a detailed report that the WHO produced after SARS.
Let us get back to mucus. Mucus forms a slimy membrane which covers the lung so that it is moist as you breathe. The lungs need to remain moist always, to avoid friction perhaps.
The cilia attached on to the mucus are like rakes such that when they move they clear dust, or viruses or pollen and other irritants that interfere with the air cleaning function of the lungs.
The moment SARS-CoV-2 gets into the body it kills these two cells. When they die, they drop to the lungs, which are like little buckets, and fill it with all that garbage and fluid.
Unlike other respiratory viruses which infect only the upper or lower airways, SARS-CoV-2 has the agility and ability to affect both the upper and lower parts of the lung.
This is when the patient has developed pneumonia and will complain of shortness of breath, and may succumb to the disease.