Theresa Chowanietz (3rd Year BSc Biomedical Science student)
"MERS Coronavirus Particles" by National Institutes of Health (NIH) is licensed under CC BY-NC 2.0
Background
On 7th January 2020, 2019-nCoV, an emerging and rapidly evolving novel coronavirus, was identified by Chinese authorities as the causative virus of a patient suffering with pneumoniae with unknown aetiology in Wuhan City, Hubei Province, China. As of 22nd January 2020, more than 500 confirmed infections and 17 deaths have been reported in China alone, with a handful of exported cases reported in Thailand, Japan, South Korea, Taiwan and the United States (CDC, 2020). However, experts at the MRC Centre for Global Infectious Disease Analysis at Imperial College London have suggested that the number of individuals suffering with the virus in Wuhan City may actually be closer to 4000 (Imai et al., 2020). With the rapid increase in cases being reported globally and Lunar New Year celebrations at the end of the month threatening to increase these numbers drastically, the US Centres for Disease Control and Prevention (CDC) raised their interim travel health notice from Level 1 (practice usual precautions) to Level 2 (practice enhanced precautions) for this destination, suggesting those with underlying health conditions are at greater risk of contracting severe disease(CDC, 2020).
Coronaviruses are commonly found circulating within animal populations, of which 7 are known to cause infection in humans. Occasionally these animal viruses may evolve and spread between human populations leading to large and severe outbreaks of disease. This was last seen in 2012 when an outbreak of MERS-CoV (Middle East respiratory syndrome coronavirus) led to an estimated infection fatality ratio of 35% (ECDC, 2020). 2019-nCoV, like other coronaviruses, is an enveloped positive-sense RNA virus which primarily targets epithelial cells of the respiratory and gastrointestinal tracts (Fehr and Perlman, 2015).
Similar to SARS-CoV (Severe Acute respiratory syndrome coronavirus) and MERS-CoV, 2019-nCoV belongs to genus Betacoronavirus, subgenus Sarbecovirus, and can cause acute respiratory illnesses in humans upon zoonotic transmission (ECDC, 2020). Reports have suggested that 2019-nCoV may be associated with a seafood and live animal market in Wuhan, China and therefore suggests zoonotic transmission may be the cause of the outbreak. A small number of affected individuals who cannot be linked directly to the Wuhan market suggests that there is also limited human-to-human transmission occurring (CDC, 2020).
How is it transmitted?
Coronaviruses have the potential to transfer from animals to human (zoonotic transmission). In rare cases coronaviruses may evolve to infect new species by adapting to different receptors on host cells. Only two beta coronaviruses (a sub-group of coronavirus) have been previously confirmed to have adapted to infect humans (SARS and MERS), however reports suggest that the 2019-nCoV outbreak is due to this same zoonotic mode of transmission and so environmental hygiene of public places has been strengthened in China. The virus may also be acquired through the consumption of contaminated raw meat, milk and animal organs (CDC, 2020).
There is a high level of uncertainty regarding the transmission of 2019-nCoV from human-to-human. Typical modes of human-to-human transmission include coughing and sneezing, close personal contact, fomites and faecal-oral contamination. On 17th January 2020, the EU’s European Centre for Disease Prevention and Control (ECDC) (ECDC, 2020) declared a very low risk of nosocomial transmission and there had been no reported cases of transmission to healthcare workers. By 22nd January 2020 there had been 15 confirmed healthcare workers infected with the virus.
What are the signs and symptoms of infection?
On average patients with 2019-nCoV develop flu like signs and symptoms within 14 days of contact. This includes a viral incubation period of 5-6 days and a 4-5 day delay from symptom onset to detection (Imai et al., 2020). They may initially present with a fever along with respiratory ailments such as coughing, shortness of breath, sore throat and a runny nose (Australian Government Department of Health, 2020). Those who have compromised immune systems may develop more serious infections leading to pneumoniae, severe acute respiratory syndrome, kidney failure and in a few cases death (WHO, 2020b).
How is the virus diagnosed?
Viral confirmation is based on clinical features and serological and molecular diagnostic methods. A real time reverse transcription-polymerase chain reaction has been developed to amplify and detect the presence of 2019-nCoV. Serum testing at both acute and convalescent phases of disease progression allow clinicians to evaluate and confirm an immunological response to 2019-nCoV specifically (WHO, 2020a).
Healthcare professionals should follow guidelines when diagnosing patients suspected of a 2019-nCoV infection. Those who present all clinical features of the virus may only be investigated when it has been established that they have recently (in the past 14 days) visited Wuhan City, China, or been in contact with a patient under investigation for 2019-nCoV. Alternatively, patients are investigated if they present some of the clinical features but have in the past 14 days been in contact with a laboratory-confirmed 2019-nCoV infected patient.
Is there any treatment available?
To date, there is no vaccine or specific treatment available for 2019-nCoV. Therefore, disease management via supportive care at home or within hospital settings is currently the only option. Due to the unknown and unpredictable evolutionary abilities of coronaviruses, vaccine production against a novel coronavirus is extremely difficult.
Preventable measures?
In order to prevent exposure to 2019-nCoV, it is advised to maintain basic hygiene procedures such as using soap and water when washing hands, coughing into elbow or tissue, not touching face or mouth and avoiding contact with potentially infected individuals. Chinese authorities have implemented isolating those infected, airport screening measures and advised the public to avoid large crowds in order to control viral spread. Other precautionary measures include not travelling to high incidence areas such as Wuhan City. Maintaining environmental hygiene especially around food stalls and farmers’ markets as well as making sure food is thoroughly cooked before eating is also important. On a global level increasing surveillance and awareness of 2019-nCoV will help to prevent the further spread of infection (WHO, 2020c).
References
AUSTRALIAN GOVERNMENT DEPARTMENT OF HEALTH (2020) Novel coronavirus. [Online] Available from: https://www.health.gov.au/health-topics/novel-coronavirus [Accessed 22 Jan. 2020].
CDC (CENTERS FOR DISEASE CONTROL AND PREVENTION) (2020) 2019 Novel Coronavirus (2019-nCoV), Wuhan, China. [Online] Available from: https://www.cdc.gov/coronavirus/2019-nCoV/summary.html [Accessed 22 Jan. 2020].
EUROPEAN CENTRE FOR DISEASE PREVENTION AND CONTROL, (ECDC) (2020) Risk Assessment: Cluster of pneumonia cases caused by a novel coronavirus, Wuhan, China . [Online] Available from: https://www.ecdc.europa.eu/sites/default/files/documents/Risk%20assessment%20-%20pneumonia%20Wuhan%20China%2017%20Jan%202020.pdf [Accessed 22 Jan. 2020].
FEHR, A.R. and PERLMAN, S. (2015) Coronaviruses: an overview of their replication and pathogenesis. Methods in Molecular Biology (Clifton, N.J.), 1282, pp. 1-23.
IMAI, N., DORIGATTI, I., CORI, A., DONNELLY, C., RILEY, S., FERGUSON, N. M. (2020) Report 2: Estimating the potential total number of novel Coronavirus cases in Wuhan City, China: MRC Centre for Global Infectious Disease Analysis, J-IDEA, Imperial College London, UK. Available from: https://www.imperial.ac.uk/mrc-global-infectious-disease-analysis/news--wuhan-coronavirus/ [Accessed 22 Jan. 2020].
WORLD HEALTH ORGANISATION (2020a) Laboratory testing for 2019 novel coronavirus (2019-nCoV) in suspected human cases. [Online] [Accessed 22 Jan 2020].
WORLD HEALTH ORGANISATION, (2020b) Coronavirus. [Online] [Accessed 22 Jan. 2020].
WHO (WORLD HEALTH ORGANISATION) (2020c) Infection Prevention and Control. [Online] Available from: https://www.who.int/csr/disease/coronavirus_infections/prevention_control/en/ [Accessed 22 Jan. 2020].
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