LETTER TO EDITOR
|Year : 2020 | Volume
| Issue : 1 | Page : 5-7
Coronavirus disease-2019: A brief compilation of facts
Department of Oral Pathology and Microbiology, ESIC Dental College, Delhi, India
|Date of Submission||07-Apr-2020|
|Date of Acceptance||07-Apr-2020|
|Date of Web Publication||08-May-2020|
Department of Oral Pathology and Microbiology, ESIC Dental College, Rohini Sector.15, Delhi - 110 089
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Saxena S. Coronavirus disease-2019: A brief compilation of facts. J Oral Maxillofac Pathol 2020;24:5-7
With the current outbreak of the Coronavirus Disease-2019 (COVID-19) pandemic, I would like to present a brief compilation of current knowledge about the virus and the disease.
Coronaviruses are a large family of viruses that can cause illness ranging widely in severity. The first known severe illness caused by a coronavirus (CoV) was the severe acute respiratory syndrome (SARS) epidemic in China in 2003. A second outbreak of severe illness occurred in 2012 in Saudi Arabia called the Middle East Respiratory Syndrome (MERS).
In December 2019, China alerted the World Health Organization (WHO) of an outbreak of severe respiratory disease, which was subsequently found to be caused by a novel betacoronavirus of the same subgenus as SARS-CoV and named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).
Shortly after the epidemic began, Chinese scientists sequenced the genome of SARS-CoV-2 and made the data available to researchers worldwide. Scientists at several other research institutions used these sequencing data to explore the origins and evolution of SARS-CoV-2. Based on their genomic sequencing analysis, researchers concluded that the most likely origins for SARS-CoV-2 followed one of two possible scenarios.
In one scenario, the virus evolved to its current pathogenic state through natural selection in a non-human host and then jumped to humans. This is how previous coronavirus outbreaks have emerged, with humans contracting the virus after direct exposure to civets (SARS) and camels (MERS). The researchers proposed bats as the most likely reservoir for SARS-CoV-2, as it is very similar to a bat coronavirus. There are no documented cases of direct bat-human transmission, however, suggesting that an intermediate host was likely involved between bats and humans. In this case, the current epidemic would probably have emerged rapidly as soon as humans were infected, as the virus would have already evolved the features that make it pathogenic and able to spread between people.
In the other proposed scenario, a nonpathogenic version of the virus jumped from an animal host into humans and then evolved to its current pathogenic state within the human population. For instance, some coronaviruses from pangolins, armadillo-like mammals found in Asia and Africa, have an receptor-binding domain (RBD) structure very similar to that of SARS-CoV-2. A coronavirus from a pangolin could possibly have been transmitted to a human either directly or through an intermediary host such as civets or ferrets.
If the SARS-CoV-2 entered humans in its current pathogenic form from an animal source, it raises the probability of future outbreaks, as the illness-causing strain of the virus could still be circulating in the animal population and might once again jump into humans. The chances are lower of a nonpathogenic coronavirus entering the human population and then evolving properties similar to SARS-CoV-2.
The scientists analyzed the genetic template for spike proteins, armatures on the outside of the virus that it uses to grab and penetrate the outer walls of human and animal cells [Figure 1]. More specifically, they focused on two important features of the spike protein: The RBD, a kind of grappling hook that grips onto host cells, and the cleavage site, a molecular can opener that allows the virus to crack open and enter host cells.
| Evidence for Natural Evolution|| |
The scientists found that the RBD portion of the SARS-CoV-2 spike proteins had evolved to effectively target a molecular feature on the outside of human cells called ACE2, a receptor involved in regulating blood pressure. The SARS-CoV-2 spike protein was so effective at binding the human cell, that the scientists concluded that it could only be a result of natural selection rather than a product of genetic engineering as suspected initially.
The SARS-CoV-2 virus mainly transmits through droplets and aerosol generated by coughing or sneezing. It also has the potential to be transmitted from fomites and surfaces contaminated by the virus as it is known to survive drying on inanimate objects for several hours.
The disease caused by SARS-CoV-2 called COVID-19 has rapidly disseminated worldwide, with clinical manifestations ranging from mild respiratory symptoms to severe pneumonia and a fatality rate estimated around 2%. Most people infected with the COVID-19 virus experience mild-to-moderate respiratory illness and recover without requiring special treatment. Older people and those with underlying medical problems such as cardiovascular disease, diabetes, chronic respiratory disease and cancer are more likely to develop serious illness.
Person-to-person transmission is occurring both in the community and health-care settings. As of April 7, 2020, nearly 1,349,784 COVID-19 cases have been documented globally, 74,820 deaths reported and 286,664 cases recovered, although many more mild cases have likely gone undiagnosed.
The ongoing outbreak presents many clinical and public health management challenges due to limited understanding of viral pathogenesis, risk factors for infection, natural history of disease including clinical presentation and outcomes, prognostic factors for severe illness, period of infectivity, modes and extent of virus interhuman transmission, as well as effective preventive measures and public health response and containment interventions. There are neither antiviral treatments nor vaccines available, but fast-track research and development efforts including clinical therapeutic trials are ongoing across the world.
Measures such as hand hygiene, respiratory etiquette and social distancing are recommended as essential steps in the prevention of infection, while home or hospital quarantine as well as restrictions on movement (lockdown) helps in preventing the spread of the disease.
Isolation and supportive therapy including ventilatory support are the mainstays of treatment of infected patients.
| Implications in Dentistry|| |
In the light of the WHO declaring the COVID-19 to be a pandemic, the Indian Dental Association (IDA) recommends preventive measures for dental professionals to minimize transmission through contact and dental procedures. Dental care settings invariably carry the risk of COVID-19 infection due to the specificity of its procedures, which involves face-to-face communication with patients, frequent exposure to saliva, blood and other body fluids and the handling of sharp instruments. Droplet and aerosol transmission of SARS-CoV-2 are the most important concerns in dental clinics and hospitals because it is hard to avoid the generation of large amounts of aerosol and droplet mixed with patient's saliva and even blood during dental practice.
Adequate patient screening and scheduling only emergency procedures are recommended. Personal protection and usage of N95 respirators or similar respirators should be used along with appropriate cough etiquettes, hand hygiene, workplace sanitization and waste disposal that must be followed as recommended by the IDA.
| Caution for Pathologists|| |
Certain precautions are to be taken by pathologists for handling specimens or reporting slides as Covid-19-infected samples may be submitted to laboratories.
- Grossing and tissue processing should be done using gloves, surgical masks and disposable operating gowns and caps. Avoid splatter or splash of formalin and other liquids during the procedure
- Wear gloves while handling slides and avoid touching the face, eyes, nose or mouth during microscopy
- Wear surgical masks while viewing the slides under the microscope
- Wear protective eye glasses during microscopy and try not to share microscope with multiple users
- Disinfect the microscope before and after use. Sanitizer in gauze can be used to wipe the microscope and cover the microscope with its plastic cover after using it
- Usage of stationery items such as pens, biopsy forms and reporting sheets should be done carefully preferably with gloved hands and clean hands with soap and water after handling these items.
These are the general precautions that all dental professionals need to take during these times of Covid-19 pandemic. As is said, “Prevention is better than cure,” so the dental professionals have to provide the best of service to patients but not at the risk of one's own safety and without compromising on the safety of the family members and the staff of dental operatories.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
COVID-19 Coronavirus Epidemic Has a Natural Origin. Science Daily; 17 March, 2020.
Coronavirus Disease (COVID 19): Pathophysiology, Epidemiology, Clinical Management and Public Health Response. Available from: http://www.frontiersin.org
. [Last accessed on 2020 Apr 07].