Coronaviruses

(Scroll down for an update posted on 29/03/2020.)

With the ongoing COVID-19 outbreak, TBL felt that it would only be apt to have a discussion on the tiny microbes that are currently making a huge impact on global healthcare, travel, trade and economy.

Viruses are tiny infectious microorganisms that can infect any living organism (including animals, plants and bacteria). They require a living host in which to replicate and stay alive, and are usually pathogenic. Their genetic material could be in the form of double-stranded DNA (deoxyribonucleic acid), like ours, or single-stranded RNA (ribonucleic acid). Viruses function by entering the target cells of the host and using their resources to multiply and thrive, usually destroying the host cell in the process.

Coronaviruses are a class of viruses that are characterised by the presence of an envelope of bulb-like surface projections. These projections give it a crown-like appearance when viewed under an electron microscope, hence earning it the prefix of ‘corona’, meaning crown in Latin. There are hundreds of types of coronaviruses that can cause disease in mammals, birds and humans. In humans, coronavirus infections often cause respiratory diseases, which range from the common cold to the more complex severe acute respiratory syndrome (SARS).

There are now seven known strains of human coronaviruses:

  • HCoV-229E (Human coronavirus 229E) – one of the strains that can cause common cold
  • HCoV-OC43 (Human coronavirus OC43) – another strain that can cause common cold
  • HCoV-NL63 (Human coronavirus NL63) – which can cause mild upper or severe lower respiratory tract infections, bronchiolitis and croup
  • HCoV-HKU1 (Human coronavirus HKU1) – which can cause bilateral pneumonia with acute respiratory disease
  • SARS-CoV (Severe acute respiratory syndrome coronavirus) – which cause SARS
  • MERS-CoV (Middle Eastern respiratory syndrome coronavirus) – which causes MERS
  • SARS-CoV-2 (currently also known as COVID-19 virus) – which caused the ongoing outbreak which started in Wuhan, China

Some coronaviruses are zoonotic and can be transmitted between humans and animals. They may be asymptomatic or cause upper respiratory, gastrointestinal or urogenital infections in their animal host, and then jump to humans and cause disease in the new host. This phenomenon is referred to as a spillover. The SARS-CoV, MERS-CoV and SARS-CoV-2 are such examples. SARS-CoV is believed to have originated in bats and reached humans through civet cats, while MERS-CoV reached humans via domesticated camels.

Symptoms

There are some common symptoms that may be observed in coronavirus infections, including:

  • fever
  • cough
  • shortness of breath
  • difficulty breathing

Complications

Coronavirus infections are usally more straightforward and treatable in younger and healthier individuals. Complications may arise predominantly in older, immunocompromised patients, including:

  • pneumonia
  • severe acute respiratory syndrome
  • renal failure
  • death

While the ongoing COVID-19 outbreak (75, 282 confirmed cases, 2,012 recorded deaths – as at 19/02/2020) has superseded the number of deaths recorded during the SARS outbreak of 2002-2004 (8,437 confirmed cases, 813 recorded deaths), it is important to understand that the mortality rate of COVID-19 is less than that of the SARS outbreak. However, the morbidity of the current outbreak is far more than that of 2002. This could be due to several reasons such as a higher virulence of the SARS-CoV-2 strain, greater population density in the location of origin, a longer incubation period (2-7 days for SARS-CoV, 2-14 days for SARS-CoV-2) during which more hosts could unknowingly get infected. Understandably, with increased population and global travel and interaction, this warrants for concern – and in some cases causes panic – among the human population.

Transmission

Spread of coronavirus infection happens by droplet transmission. That is, infected droplets may be released from a patient when sneezing, coughing, or even talking, and may reach another person either directly (when breathing in or swallowing) or via fomites. Touching surfaces such as tabletops and doorknobs, that have been contaminated by an infected person, or shaking their hand, and then touching one’s face can easily facilitate viral transmission between people.

How long a virus can remain viable outside of a host depends on the strain of the virus and the surface on which it falls. Most viruses can survive on solid surfaces for around 24 hours, however there is speculation that some coronaviruses can last up to a few days on such surfaces.

Prevention

As mentioned earlier, elderly and immunocompromised individuals seem to be more susceptible to complications arising from coronavirus infections, and therefore should be given more attention in the prevention and treatment of infection.

As with the common cold, the following preventive measures could be implemented:

If you experience the symptoms of a respiratory disease, always remember to:

  • cough into your elbow or sleeve, NOT into your hands
  • blow your nose/cough into a tissue and dispose of it immediately
  • wash your hands with soap regularly
  • wash your hands well after using the bathroom as excretory matter also carries infection
  • refrain from going out, particularly to public and crowded places – wear a face mask if you must
  • practise self-isolation in the event symptoms experienced during outbreaks of this nature

If you notice someone with these symptoms:

  • maintain a safe distance from them and try not to come into any sort of direct contact
  • do not share clothes, towels, cutlery, cups, etc.
  • do not touch your face as you might have touched a contaminated surface
  • disinfect surfaces (tabletops, doorknobs, linen) where an infected person may have been
  • wash your hands well with soap or use a hand sanitiser as soon as possible
  • wear a face mask when you go out of the house in the event of such outbreaks

Diagnosis

Diagnosis of coronavirus infections have been made largely on the basis of observable symptoms – increased temperature, cough, difficulty breathing – as this is quicker for testing larger crowds. However, there are more specific laboratory diagnostic tools such as:

  • throat or nasal swabs to detect the presence of the coronavirus
  • PCR testing to detect the presence of specific antibodies
  • lung scanning to detect pneumonia-related patches in the lungs

The method used depends on several factors such as availability of test kits, number of suspected cases that are to be tested, time available (lab tests take time to produce results).

Treatment

While there is no straightforward treatment, some measures to practise include:

  • getting extra rest and sleep as the body’s immune system uses up more energy to fight the infection
  • taking plenty of fluids to stay hydrated – water, soups, fresh juices
  • gargling with salt water to ease throat soreness
  • using lozenges to ease cough and throat soreness
  • keeping track of body temperature and getting medical attention if temperature keeps increasing or does not drop
  • seeking immediate medical attention in the event of severe symptoms
  • support from a ventilator may be required in severe cases

The fact is, there have been far more deaths caused by the influenza virus (14,000 recorded deaths in the USA alone – as at 18/02/2020) during the 2019-2020 flu season. While this is a grave situation, there is less light shed on it and definitely less panic stirred by the idea of catching the flu. One reason for this could be the fact that there is an annual seasonal vaccination available against the flu, giving people a sense of confidence in familiarity and awareness. We are also more prepared for flu season, as opposed to the sudden outbreak of a completely new and unknown virus – causing a fear of the unknown. There are anti-viral medication options available against the flu too, which are particularly effective against vaccinated individuals. So, while this seasonal bug seems to be wreaking havoc of sorts too, it is still somewhat seen as ‘the known devil’, giving us humans a better sense of control in terms of dealing with it.

Update (29/03/2020):

Much has happened since this article was published.

SARS-CoV-2 has made it more than clear that it does not wish to be compared with the seasonal influenza virus – or any other existing virus for that matter. Fatality associated with COVID-19 (~1%) is about 10 times that of seasonal influenza (~0.1%).

As of this moment, 665,164 cases have been confirmed around the world, causing 30,852 deaths, and out of which just 140,225 recoveries have been recorded.

A total of 177 countries/regions have been affected, with several countries closing borders and many cities or regions imposing curfews of lockdowns.

No country or region has been spared – after dealing a heavy blow on China, it is now blazing through Europe and the USA. The Middle East, sub-continental Asia, Australasia, Africa, South America and every nook and cranny of the planet are keeping their fingers crossed and fighting hard to be spared of a similar situation.

No race, creed, caste or title has been spared, with celebrities, royalty and world leaders being affected just as much as the man in poverty.

Economies around the world are plummeting.

Health services have been overwhelmed and medical staff have had to carry out the gut-wrenching task of choosing between patients to administer treatment or facilities. Shortages of ventilators for patients, test kits for suspected cases and personal protective equipment (PPE) for medical staff have challenged the human fight against this pandemic.

As a result, much of the older generations of countries like Italy and Spain have been lost to the disease – taking with them a part of history and culture, and memories of life spent in a world when it was at its best.

And yet, the numbers are an underestimation of the reality of the situation. Asymptomatic carriers are in plenty, as are unrecorded symptomatic cases who have not been tested and ‘confirmed’ due to shortages of test kits.

On a positive note, the Earth is healing while the human species fights to survive. Air pollution levels have dropped, and the ozone is benefitting from it without a doubt.

And on a more philosophical than scientific level, mighty mankind has been brought to its knees by a single microorganism.

Cover illustration adapted from Newsday.

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