Shakil Ahmad Wani
We are struggling to understand how the novel coronavirus tears through the human body. We know that it reaches for the lungs but it can also reach the heart and blood vessels, kidneys, gut and brain. Despite lot of information flowing in, a clear picture is still elusive as the virus acts like no microbe humanity has ever seen. “We need to keep a very open mind as this phenomenon goes forward,” says Nancy Reau, a liver transplant physician who has been treating Covid-19 patients at Rush University Medical Center. The causative agent of Covid-19 is an invisible creature of such small size that the tip of a needle can accommodate lakhs of them.
How the infection begins
When a Covid patient expels virus-laden droplets and someone else inhales them, the novel SARS-CoV-2 enters the nose and throat. It finds a welcome home in the lining of the nose, because cells here are rich in a cell-surface receptor called angiotensin-converting enzyme 2 (ACE2) which the virus uses as hook to attach itself to and enter the host cell. The ACE2 molecule, widely distributed, is primarily responsible for regulation of blood pressure in our body. However, it makes tissues susceptible to Covid-19 virus infection. Once the virus enters the cell, it takes control of the cell’s machinery for its multiplication and release for invading neighbouring cells. As the virus multiplies, an infected person may shed copious amounts of it, especially during the first week or so. Symptoms may or may not be present at this point. Or the victim may develop fever, dry cough, sore throat, loss of smell and taste, or head and body aches. If the immune system doesn’t beat back the virus during this initial phase, it then marches down the windpipe to attack the lungs, where it can turn deadly.
The virus, or the body’s response to it, can injure many other organs. Scientists are just beginning to probe the scope and nature of that harm. The virus is more interested in having fresh victims than in producing symptoms in the infected one. Thus asymptomatic infected persons in the population are not a surprise.
The basic unit of our respiratory tree is called alveoli (air sacs) where the actual gaseous exchange takes place in lungs. Each alveolus is lined by a single layer of cells that are also rich in ACE2 receptors. It is here that oxygen crosses the alveoli into the capillaries, tiny blood vessels that lie beside the air sacs. The oxygen is then carried to the rest of the body. However, as the immune system wrestles with the virus, it turns into a battle field and damages healthy tissue and disrupts this oxygen transfer. Front-line blood cells called neutrophils at the site release chemical molecules called chemokines. This in turn recruits more immune cells at the site to target and kill the virus-infected cells, leaving a mass of dead cells and pus behind. This sets in pneumonia, with its corresponding symptoms: coughing, fever, and rapid, shallow respiration. Some Covid-19 patients recover, sometimes with no more support than oxygen breathed in through nasal prongs. But some deteriorate, often quite suddenly, developing a condition called acute respiratory distress syndrome (ARDS). Oxygen levels in their blood drop and they struggle ever harder to breathe. Commonly, these patients end up on ventilators. Many die. Autopsies show their alveoli stuffed with fluid, white blood cells, mucus, and the debris of destroyed lung tissue.
Some patients have extremely low blood-oxygen levels, yet are not gasping for breath. It’s possible that at some stage of disease, the virus alters the delicate balance of hormones that help regulate blood pressure and constricts blood vessels going to the lungs. So, oxygen uptake is impeded by constricted blood vessels, rather than by clogged alveoli. “One theory is that the virus affects the vascular biology and that’s why we see these really low oxygen levels,” says Joseph Levitt, a pulmonary critical care physician at the Stanford University School of Medicine.
The virus’s impact
“The disease can attack almost anything in the body with devastating consequences,” says cardiologist Harlan Krumholz of Yale University and Yale-New Haven Hospital, who is leading multiple efforts to gather clinical data on Covid-19. “Its ferocity is breathtaking and humbling.” In serious cases almost all vital organs (lungs, kidneys, liver, brain, and heart and blood vessels), being rich in ACE2 molecules, come under attack of the Covid-19 virus. In the lungs the immune cells crowd in an inflamed alveolus, whose walls break down during attack by the virus, diminishing oxygen uptake. Patients cough, fever rises, and it takes more and more effort to breathe. Because of the involvement of nose, some patients lose their sense of smell. Up to half of the hospitalised patients have enzyme levels that signal a struggling liver. Scientists say that an immune system in overdrive as well as drugs given to fight the virus may be causing damage to the liver. In severe cases kidney damage is common and makes death more likely. The virus may attack the kidneys directly, or kidney failure may be part of events like plummeting blood pressure. The virus can infect the lower gastrointestinal tract, which is rich in ACE2 receptors and 20% or more of patients may have diarrhoea. Some Covid-19 patients have strokes, seizures, mental confusion, and brain inflammation.
In the sickest patients, conjunctivitis, inflammation of the membrane that lines the front of the eye and inner eyelid is more common. Scientists are struggling to understand exactly what causes the cardiovascular damage. The virus may directly attack the lining of the heart and blood vessels, being rich in ACE2 receptors. Or perhaps lack of oxygen, due to the chaos in the lungs, damages blood vessels. This may help to explain why patients with pre-existing damage to those vessels, for example from diabetes and high blood pressure, face higher risk of serious disease. Infection can also promote blood clots, heart attacks, and cardiac inflammation. “We’re still at the beginning,” says Krumholz. “We really don’t understand who is vulnerable, why some people are affected so severely, why it comes on so rapidly … and why it is so hard [for some] to recover”.
Some clinicians suspect the driving force in many gravely ill patients is a disastrous overreaction of the immune system known as a “cytokine storm,” which other viral infections are known to trigger. In a cytokine storm, levels of certain cytokines soar far beyond what’s needed, and immune cells start to attack healthy tissues. Blood vessels leak, blood pressure drops, clots form, and catastrophic organ failure can ensue.
Divine the Sign
The Quran says that in the creation of the heavens and the earth and the alteration of night and day are signs for people of understanding (3:190). As Allama Iqbal said, “O people with observing eyes, a taste for observation is a good thing, but what good is observation if it does not see the inwardness of things”. The virus uses binds its spike protein, i.e. receptor binding domain (RBD), to the ACE2 receptor on the host cell. Dr Kristian G. Andersen from Scripps Research Institute, La Jolla, USA, says that this proficient binding is strong evidence that SARS-CoV-2 is not the product of purposeful manipulation but a natural selection. Similarly, the genetic data irrefutably show that SARS-CoV-2 is not derived from any previously used virus backbone. The interaction between RBD and ACE2 is like that of pin and socket of an electric circuit or ball and socket of our joints. The two fit optimally as their architect is one.
In History of Astronomy by A. Pannekoek (close associate of Karl Marx), a renowned Arab astronomer, Abdullah Muhammad ibn Jabir Al-Batteni (878-918), is quoted as saying, “The science of stars… tends to recognise God’s oneness and highest divine wisdom”. Amir-e Kabir mentions in Awrah: “Va ya man dalat ala wahdan-e-ti aayatu hoo (O my lord your signs are witness to your oneness).” The virus is also a sign of this oneness. It chooses a molecule (ACE2) that shows to it the route and the destination in our body. The virus does not eat, drink or inhale. It thrives on readymade products of the host cell. Who taught him this skill? Can there be a wisdom without the wise and co-ordination without a co-ordinator? Allah fulfils his designs in mysterious ways for he is all knowing (12:100).
The virus has affected people from all walks of life, from subjects to rulers, labourers to industrialists, developing and developed, without any discrimination on basis of gender, location, race, colour or creed. Nations with cutting-edge technology and booming economy are knocked down helplessly. Our lord reminds us: “Does he think that never will anyone overcome him?” (90:05). “Then will he have no might or any helper” (86:10). Doesn’t the sudden lockdown create a situation that the Quran describes as: “Which will suddenly seize them while they will be disputing (about their worldly affairs). Then they will neither be able to make their will nor be able to return to their families” (36:49-50). Isn’t Covid-19 a foretaste of coming events? I say it needs to be read in the words of Ralph Emerson who says, “All I have seen teaches me to trust the creator for all I have not seen”. Newton could realise the gravitational force by the falling of an apple. Doesn’t this pandemic signal to humanity that it is one, its goal and its fate is one? Doesn’t it counsel not to think in isolation but holistically and universally. As Socrates said, “I am not the citizen of Athens and Greece but of the Universe”. Prophet Muhammad said that this universal thinking cannot be achieved unless you treat a stranger as you treat your kin.
The pandemic teaches us that if one remains indifferent to the problem of a companion or neighbour, he will be the next to face it. This has been the message loud and clear: “Worship Allah and associate nothing with Him, and show kindness and affection to parents, and be kind to near relatives, orphans, the needy, the neighbours – kinsmen or strangers, the companions at your side, the wayfarer. Indeed, Allah does not like those who are self-deluding and boastful (4:36).”
As Shakespeare puts it, God brings men into deep water not to drown them but to cleanse them. The Quran reveals that the creator has given us responsibility with power on this planet. “And it is He who has made you vicegerents upon the earth and has raised some of you above others in ranks so that he may test you in what he has given you. Indeed your lord is swift in inflicting punishment yet he is also very forgiving and merciful”.
These are trying times, but they’ll be easier if we be patient, improve ourselves, and do what we can to support one another. Finally, Allah is with the righteous and the patient.
The writer is former Director Education, SKUAST-Kashmir.