What   the   medical   profession   is   seeing   today   has   not   been   witnessed   in   over   a century.   A   viral   infection   for   which   no   curative   treatment   is   available   spread rapidly   and   has   now   become   endemic.   It   emerged   from   China   a   few   months ago   to   cripple   the   whole   world   today.   The   last   time   such   an   endemic   occurred was in 1918 when the Spanish Flu killed over 25 million people. Viruses: Viruses   cause   a   variety   of   infection   from   a   simple   cold   to   the   deadly   Ebola infection.    Most    of    the    serious    diseases    caused    by    them    have    now    been conquered   through   suitable   vaccines.   However   every   now   and   again   a   new form    evolves.    Most    of    these    are    tackled    effectively    by    the    body’s    own immune   system.   Unfortunately   a   deadly   form   evolves   from   time   to   time   when   the   body’s   immune   system   is   unable   to   fight   it. The new Corona Virus that causes “Covid 19” infection is one such. It is a respiratory virus. How is the “New Corona Virus” different   We   have   known   about   Corona   Viruses   for   more   than   50   years.   So   why   are   we   panicking   about   this   new   virus.   By   exposure   to many   types   of   corona   viruses   in   the   past,   our   body’s   defence   mechanism   has   acquired   suitable   antibodies   to   fight   an   invading virus   that   is   similar   to   the   ones   that   it   has   encountered   before. The   New   Corona Virus   on   the   other   hand   is   completely   different   to the   ones   that   the   body   has   been   exposed   to   before.   Therefore   it   does   not   have   a   ready   antibody   to   fight   the   newcomer.   The immune   system   has   to   generate   a   new   antibody   to   fight   the   virus   and   that   may   take   a   few   days.   In   addition   to   that   the   binding capacity   (fusion)   of   the   new   corona   virus   to   human   cells   appears   to   be   more   than   100   times   stronger   than   those   of   any   previously known corona viruses. Effect of the virus when it enters the human body: The   virus   is   so   named   because   it’s   surface   is   covered   by   bulbous   projections   that   look   like   a crown   when   viewed   by   an   electron   microscope.   It   is   0.125   micron   in   diameter   (human   hair   is 100   microns).   The   surface   projections   are   made   up   of   protein   that   contains   the   infective material   (the   virion).   When   an   infective   droplet   is   inhaled,   the   virus   can   reach   any   area   from the   throat   to   the   lung   (the   alveolus).   For   the   virus   to   multiply   and   infect   the   individual   it   must first enter the living cell. The   glycoprotein   spikes   on   the   virus   fuse   to   a   suitable   host   cell   and   inject   the   infective material   in   to   the   cell.   An   enzyme   called   ACE2   which   is   present   on   certain   cell   membranes like   the   lungs,   arteries,   kidneys   and   intestines   facilitates   the   spikes   to   fuse   with   the   cell.   Once inside   the   host   cell   they   start   replicating.   The   genetic   material   of   the   virus   then   makes   the   cell produce   several   copies   of   the   virus.   The   new   copy   can   then   enter   an   adjacent   cell   and   repeat the process. Thus within a short time the virus multiplies in to millions and starts spreading. Symptoms   of   someone   infected   with   the   virus   may   vary   from   dry   cough,   fever   or   difficulty   in   breathing.   Some   may   even complain   of      loss   of   taste   or   smell.   If   the   individual   is   young   and   healthy   it   may   cause   only   mild   symptoms   affecting   the   upper respiratory   tract   giving   rise   to   fever   or   bouts   of   coughing.   However   if   they   have   other   co-existing   conditions   like   high   blood pressure,   diabetes,   chronic   respiratory   disease,   obesity   or   if   their   immunity   is   compromised   as   when   receiving   treatment   for cancer   etc.   the   person   may   develop   a   more   serious   form   of   the   disease   affecting   the   lung.   Older   generation   are   also   prone   to develop a more serious form of the disease. When   the   lungs   are   affected,   the   lining   membrane   of   the   alveoli   becomes   inflammed   giving   rise   to   pneumonia. This   results   in   the alveoli   becoming   filled   with   fluid   and   inflammatory   cells.   This   affects   the   exchange   of   gases   in   the   lung   causing   reduced   amount of   oxygen   being   carried   in   the   blood. When   the   disease   progresses   further,   more   of   the   lung   is   affected. When   the   oxygen   level   in the blood drops below a critical level all the major organs can start to fail leading to death. Diagnostic tests for COVID 19:  (fall into two broad categories) 1 . Swab   Test:   Molecular   tests   or   Nucleic   acid   test   of   secretions   from   the   nose   and   throat   will   detect   the   virus’   genetic code. 2 . Blood Test: Immunoassay will detect proteins (antigens or antibodies) associated with the virus. Nucleic    acid-based    tests     are    the    most    sensitive    for    early    detection    of    infection.    The    test    is    called    real    time    reverse transcription–polymerase   chain   reaction   ( real   time   RT-PCR ).   It   is   one   of   the   most   accurate   laboratory   methods   for   detecting, tracking,   and   studying   the   corona   virus. A   swab   from   an   individual   will   collect   mucous,   saliva,   bits   of   cells   and   with   it   viral   RNA if   it   is   present. The   sample   is   then   processed   in   the   lab.   Results   are   usually   available   within   a   few   hours.   Newer   machines   that   can give you the result in under an hour are being developed and will soon be available on the market. Immunoassay:   Usually   blood,   plasma,   or   serum   is   used   for   the   test.   Immunoassay   detects   the   presence   of   specific   immune proteins.   The   tests   check   for   antigen   or   antibody   in   the   specimen.   Antigens   are   from   the   virus   and   antibodies   are   from   the patients   immune   system.   The   tests   use   both   virus   specific   antigen   or   antibody   for   the   immunoassay.   During   the   early   stage   of infection   the   viral   antigens   circulating   in   the   blood   will   react   with   the   antibody   used   in   the   test   to   indicate   that   the   patient   is infected.   This   is   the   basis   for   many   of   the   “Rapid   Antibody   Tests”.   A   few   days   after   an   infection   the   patient   is   likely   to produce   antibodies.   These   antibodies   will   react   with   viral   specific   antigen   to   indicate   the   presence   of   ongoing   or   past   viral infection. At   the   moment   Immunoassay   aren’t   as   sensitive   as   nucleic   acid   tests   to   detect   infection   during   the   early   stages.   However   they   are easier   to   use   and   would   indicate   that   the   individual   became   infected   or   was   exposed   to   the   infection   a   few   days   (or   weeks)   before the test. The test will be very useful for surveillance rather than for diagnosis. Corona   viruses   are   the   common   cause   of   colds   and   other   upper   respiratory   infections   everywhere.   Novel   Corona   Virus   (the   new corona   virus)   is   an   altered   form   of   the   same   virus   that   can   cause   a   serious   disease   that   could   turn   fatal.   So   how   do   we   know   that the   cold   or   cough   that   you   have   developed   is   not   the   usual   ordinary   cold   or   cough.   Unless   you   are   tested   you   may   not   know.   The general   advice   now   is,   start   treating   any   cold   or   cough   with   simple   medication. As   a   precaution   isolate   yourself   from   the   rest   of the   family,   as   you   may   still   be   infected   with   mild   symptoms.   Most   people   have   only   mild   illness   and   usually   recover   at   home without   medical   care. As   the   incubation   period   for   the   virus   can   be   up   to   14   days,   isolation   should   be   for   14   days.   However   if   you develop a high fever, have difficulty controlling your cough or have difficulty breathing, you must request urgent medical help. If   you   are   over   70   or   have   other   co-morbid   conditions   like   hypertension,   diabetes,   asthma,   obesity   or   chronic   heart   disease   you have   to   be   extra   careful   and   call   for   medical   advice   if   any   of   the   above   mentioned   symptoms   are   getting   worse..   Do   not   wait   until you have difficulty breathing. Treatment: Most   people   who   get   infected   will   recover   well   at   home.   All   that   is   necessary   is   to   isolate   yourself   from   other   family   members and   treat   the   infection   as   you   would   for   a   flu   or   cold. As   of   now   there   is   no   specific   drug   that   will   cure   the   disease.   Paracetamol (acetaminophen) (max 3000 milligrams/day) can be prescribed for the pain and fever that may accompany the disease. Hydroxychloroquine   and   chloroquine   have   been   shown   to   inhibit   the   virus   from   entering   the   cell.   It   has   also   been   reported   that   it would   kill   the   virus   within   the   cell.   However   it   does   not   help   everyone   and   also   they   have   other   side   effects   on   the   heart   etc   and therefore not suitable for everyone. Until   the   scientists   come   up   with   a   definite   drug   to   cure   the   disease   the   main   management   now   is   to   make   sure   the   patient   is comfortable,   well   hydrated,   on   a   good   diet   and   well   oxygenated.   Antibiotics   are   necessary   only   when   they   develop   secondary bacterial infection following pneumonia. Hospital Treatment: According   to   WHO   80%   of   patients   who   have   tested   positive   recover   without   the   need   to   go   in   to   hospital.   However   for   the remaining   20%   when   symptoms   get   worse   and   breathing   becomes   difficult,   they   should   be   shifted   to   the   hospital.   Difficulty   to breathe often indicates that the pneumonia is getting worse and oxygen level in the blood is dropping. Treatment   in   the   hospital   will   consist   mainly   of   isolating   the   patient   with   intensive   support   and   administration   of   oxygen   when necessary   through   the   best   possible   means   (through   a   ventilator   if   necessary).   Suitable   antibiotics   will   be   given   to   counter secondary bacterial infection when needed. Take Home Points: • Covid 19 is a very virulent virus that spreads easily • To date there is no vaccination to prevent an infection • At the moment there is no curative medicine available to treat the infection • Avoid infection by staying away from crowds • Wear a mask to prevent spread when you are out and about • Maintain a safe distance from others in a public place • If infection is suspected in a member of family, keep them isolated for 2 weeks • Wash your hands with soap and water regularly (prevents transmission of infection) This Topic is discussed in greater detail in the “Forum” under 1. Covid 19 infection;   2. Corona Virus Part I;  3. Corona Virus Part II

K. Badrinath, FRCS

April 2020