Corona Viruses 2019, why the mutation and what can be done.

The 2019-nCoV corona virus identified in the current outbreak in the Wuhan province in China is the third virus which has mutated from animals to infect human beings. This one has been traced to a seafood market in Wuhan province. The two other pathogenic human respiratory coronaviruses are : severe acute respiratory syndrome coronavirus [SARS-CoV] and Middle East respiratory syndrome coronavirus [MERS-CoV]. As of January 24, 2020, there were more than 800 reported cases of 2019-nCoV, with a mortality rate of 3%. The viral genome has been sequenced, and these results show that it is 75 to 80% identical to the SARS-CoV and even more closely related to several bat coronaviruses. How is this going to help? Reverse transcriptase polymerase chain reaction assays can be developed for early detection in human beings before symptoms begin and in the wet markets where the spread began initially. Hence we can detect how widespread the infection is. Vaccines can be developed.

How do these viruses spread and do they all spread in the same way? Transmission of SARS-CoV and MERS-CoV occurred to a large extent by means of superspreading events. These superspreading events are diseases which occur at the same time as the virus invades the patient: the virus then uses the same pathways as the concomitant illness, in the case of SARS-CoV and 2019-CoV lower respiratory illnesses so the infection appears along with the other lower respiratory disease. SARS-CoV mutated over the 2002–2004 epidemic to better bind to its cellular receptor and to optimize replication in human cells, enhancing virulence. The frequent mutations occur because of error prone RNA-dependent RNA polymerases. MERS-CoV does not appear to mutate in this fashion. It is likely that 2019-nCoV will behave more like SARS-CoV and further adapt to the human host, with enhanced binding to hACE2. It will be necessary to study the virus at different geographical locations as well as in autopsy samples to determine the degree of mutation and virulence.

A key question is identification of the zoonotic origin of the virus. It has close similarity to bat coronaviruses, so it is likely that bats are the primary reservoir for the virus. SARS-CoV was transmitted to humans from exotic animals in wet markets, whereas MERS-CoV is transmitted from camels to humans. In both cases, the ancestral hosts were probably bats. Whether 2019-nCoV is transmitted directly from bats or by means of intermediate hosts is important to understand and will help define zoonotic transmission patterns. Fruit bats are apart of far-eastern cuisine as are other exotic animals.

Do masks help in the prevention of 2019-CoV? The paper masks being use probably do not prevent the virus from emerging from the nose into the environment but do prevent people from touching their mouths and noses, and help prevent the virus from spreading to surfaces like tables, desks etc. The best prevention is washing hands and wiping all work surfaces with an antiseptic.

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I am a Professor of Medicine and a Nephrologist. Having served in the Army Medical College, Pakistan Army for 27 years I eventually became the Dean and Principal of the Bahria University Medical and Dental College Karachi from where I retired in 2016. My passion is teaching and mentoring young doctors. I am associated with the College of Physicians and Surgeons Pakistan as a Fellow and an examiner. I find that many young doctors make mistakes because they do not understand how they should answer questions; basically they do not understand why a question is being asked. My aim is to help them process the information they acquire as part of their education to answer questions, pass examinations and to best take care of patients without supervision of a consultant. Read my blog, interact and ask questions so that I can help you more.

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