"Corona virus" - Must know things!!!

What is corona-virus?

                    Before going in detail about the coronavirus, we need to know about a term called “emerging virus”.

                    " Viruses which appear to medical scientists unexpectedly or are new are often referred to as emerging viruses”.

   I know, that you are having a question that, how these viruses are emerging. There are no easy answers to that. But, the literature is giving three main processes that might be leading to the emergence of such a virus. Those processes include:

                                     1.Mutation of the existing virus

                                     2.Dissemination of the viral disease from a small isolated population, worldwide across nations and even continents.

                                     3.Spread of existing virus from other animals to humans.

Now when coming to study about the last process we should know about a term called ”Natural Reservoir for virus”, which is nothing but the animals in which the virus is residing silently without creating the disease in the animals ( ie. The animal harbors the virus but is asymptomatic).

 To get a clear view of the aforesaid concept, let us consider a well-known example, which is nothing but the “Flu” virus which caused epidemics mercilessly in the pages of human history.

Of the influenza virus types (Type A, B, C), the only type which affects both humans and other species is type A. This type is the one that produced the epidemics previously. It is because there is a rich source of Natural reservoir available for the transmission of the virus from the zoonotic species to the human race.

With this level of awareness about the emerging virus, here comes the very recent villain to the human race, “CORONA VIRUS”.

Basic microbiology of the coronavirus:

      Coronavirus are single stranded, positive-sense RNA virus which is relatively a larger virus with diameter ranging from 80-220nm.The genome of the coronavirus the longest known so far, which are incorporated into the envelope in helical symmetry.

It is an enveloped virus which is pleomorphic (able to assume different forms) with “Spikes” with club-like or drumstick like swellings placed at regular intervals over it.

      The virus at 34°C, multiplies profusely. But, its infectivity is having an inverse relationship at very high temperatures.

      The common cold coronavirus can be cultured in human tracheal tissues and human diploid cell lines.

      Coronavirus can cause outbreaks of gastroenteritis which is characterized by non-inflammatory watery diarrhea which is usually self-limiting, most probably said to be transmitted through fecal-oral route.

     The diagnosis of this virus shall be done through direct electron microscopy of the stool samples.  

                            

Colorized transmission electron micrograph of the novel coronavirus that emerged in 2012 National Institute of Allergy and Infectious Diseases (NIAID)

                                   

Why it is named as coronavirus?

          International Committee on Taxonomy of Viruses(ICTV) is the one which gives names to virus for the systemic study all over the world. While approving the names, the virologists are creative about naming the virus.

          Our hero of interest here, “Coronavirus” got its name because of its morphology seen under electron-microscope, which shows projections/spikes on the membrane, creating a halo-like or crown-like appearance (corona, Latin for “halo” or “crown”).

Classification of the coronavirus: 
    Coronavirus contains 4 main genera viz.,

         1.   Alphacoronavirus

         2.   Betacoronavirus [includes SARS, MERS, and even the recent outbreak “Wuhan strain”]

         3.   Deltacoronavirus

         4.   Gammacoronavirus

  

There are so far 6 main strains known to have caused outbreaks which are,

         1.      Human coronavirus 229E (HCoV-229E)

         2.      Human coronavirus OC43 (HCoV-OC43)

         3.      SARS-CoV

         4.      Human coronavirus NL63 (HCoV-NL63, New Haven coronavirus)

         5.      Human coronavirus HKU1

         6.      Middle East respiratory syndrome coronavirus (MERS-CoV), previously known as novel coronavirus 2012 and HCoV-EMC.

The newly arrived strain which is currently producing outbreaks is named as,

         7.      Novel coronavirus (2019-nCoV) (It has been named as Novel, meaning newly discovered.)

Animals associated with coronavirus:

1.      Chinese horseshoe bats (genus Rhinolophus)[ natural reservoir of a SARS-like coronavirus].

Carriers of the coronavirus:

2.      Masked palm civet (Paguma  larvata) 

3.      Burmese  ferret-badger (Melogale  personata)
4.      Racoon-dog (Nyctereutes procyonoides).

Coronavirus included in the order, Nidovirales are more commonly associated with the infections (enteric/respiratory /neurological pathology), in domesticated mammals.

History and Epidemiology of Coronavirus:

         Coronavirus is said to be present in more earlier times in the history of mankind, but some literature reports its discovery, at around 1965.

 So far in history, there are two main types of coronavirus classified clinically,

                     1. One type related to common cold (2^nd most common cause of common cold in the world, around 10%), viral pneumonia and myocarditis.

                    2. Other types related to Enteric infections.

When we turn the pages of history about the coronavirus outbreaks, we cannot ignore the two main outbreaks which includes,

                                       1.SARS (Severe acute respiratory syndrome)

                                       2.MERS( Middle East respiratory syndrome)

1.SARS (Severe acute respiratory syndrome)

          In November 2002, people in China( especially in Guangdong Province of China)  began falling sick of a new respiratory disease. Nothing of this was said by the Chinese authorities until February 2004, when 305 "atypical pneumonia" cases were reported. 

          It already fled China at that time, when it was transmitted by a Guangdong resident in a Hong Kong hotel to other guests who circulated it to Montreal, Hanoi, Singapore, and elsewhere.

          It took only a few months for the pneumonia to spread to more than 25 countries in Asia, Europe, and North and South America, thanks to the ease of global travel. The World Health Organization (WHO) released a global warning on SARS in March 2004.

          In May, anyone found violating SARS quarantine orders threatened to be executed or jailed for life.

          Public health staff reacted quickly, isolating patients and quarantining those who had come into contact with them. This rapid response resulted in quenching the epidemic before it could reach a much larger population due to low infectivity and other characteristics of the SARS virus.

          By July 2003, when the outbreak had been declared over, it had spread to 29 countries, killed 774 people and infected 8,098. Of those killed, 350 were in China, none in the United States.

          Two Hong Kong and Shenzhen teams discover a Coronavirus in wild animals gathered in markets in southern China on May 23, 2003.

       Species tested positive were, the masked palm civet (Paguma larvata Smith, 1827), the Burmese ferret-badger (Melogale personata Geoffroy Saint-Hilaire, 1831) and the raccoon-dog (Nyctereutes procyonoides Gray, 1834; serological evidence only), belong to the Carnivora order and bear many coronaviruses, some very similar to [ SARS-CoV ].

        Over 10,000 civet cats, a forest animal sold in wild game markets and a popular delicacy in many restaurants were killed by the Chinese government.

        During and after the outbreak, accelerated identification and preventive steps were undertaken. Two examples of protective measures are proactive monitoring of symptoms of fever or respiratory disease at airports and the implementation of SARS-CoV vaccine trials. At the moment no particular treatment is accepted.

       The SARS outbreak in 2003 revealed the ease with which a viral infectious agent would spread to the globe.

        It is not clear if SARS-CoV was passed on directly to people (bats are eaten as a delicacy and bat feces are a traditional Asian asthma treatment) or whether they were transmitted to people through infected civets.

                             

2.MERS:

          Under the International Health Regulation (2005), the Republic of Korea told the WHO on 20 May 2015.The Regional Emergence Center was founded by WHO on 28 May 2015 and an Event Management Team was formed.

                                   

                                    PICTURE: MERS Coronavirus Particles

Transmission electron micrograph of Middle East Respiratory Syndrome virus CoV particles found in the lumen of the endoplasmic reticulum in an infected MRC-5 cell.Credit: NIAID

            In June, a joint mission was conducted by the Ministry of Health and Welfare and WHO to assess the risks posed by the outbreak and make recommendations on response measures.  The joint mission was followed by a visit by Dr. Shin Young-soo and Dr. Margaret Chan, then the WHO Regional Director and Director-General respectively.

PICTURE: Middle East Respiratory Syndrome Coronavirus particle envelope proteins immunolabeled with Rabbit HCoV-EMC/2012 primary antibody and Goat anti-Rabbit 10 nm gold particles. Credit: NIAID

          No vaccine was approved for this coronavirus. Human to human transmission is possible here.

How can we protect ourselves from coronavirus?

WHO’s standard recommendations for the general public to reduce exposure to and transmission of a range of illnesses are as follows, which include hand and respiratory hygiene, and safe food practices:

• Frequently clean hands by using alcohol-based hand rub or soap and water.
• When coughing and sneezing cover mouth and nose with flexed elbow or tissue – throw the tissue away immediately and wash hands.
• Avoid close contact with anyone who has a fever and cough.
• If you have fever, cough and difficulty breathing, seek medical care early and share previous travel history with your health care provider.
• When visiting live markets in areas currently experiencing cases of novel coronavirus, avoid direct unprotected contact with live animals and surfaces in contact with animals.
• The consumption of raw or undercooked animal products should be avoided. Raw meat, milk or animal organs should be handled with care, to avoid cross-contamination with uncooked foods, as per good food safety practices.

[SOURCE: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public]

Conclusion:

               With this idea about the coronavirus, we shall protect ourselves from the deadly infection, or shall detect the infection as earlier as possible to avail the utmost care that could be provided to us and our loved ones.

           Kindly share the post to your loved ones for them to gain knowledge about this infection.

The above article was written by:

Dr.Edward Lourdes Roshan, Cuddalore.

      

Dr.Vimal Kumar, Pondicherry.