INTRODUCTION
Coronaviruses are viruses from the family coronaviridae and subfamily
ortho coronaviridae that usually cause mild and severe respiratory
distress in man and other animals. Three types of viruses causes severe
diseases to humans; SARS-CoV that cause severe acute respiratory
syndrome, MERS-CoV that cause Middle East respiratory syndrome and the
currently discovered SARS-CoV-2 (David and Steven, 1996; CDC, 2020; NIM,
2020).
Viral respiratory illness commonly known as severe acute respiratory
syndrome is caused by SARS associated coronavirus (SARS-CoV) generally
called SARS virus. It is a recently recognized febrile respiratory
illness that first appeared in Guangdong Province, southern part of
People’s Republic of China in November 2002 (Sampathkumar et al., 2003;
Kang et al., 2005; Maschinen et al., 2005), has since spread to more
than two dozen countries in North America, South America, Europe, and
Asia. The SARS global outbreak contained (CDC, 2017) has resulted in a
cumulative total of 8422 cases, with 916 deaths reported from 29
countries during the outbreak (Sampathkumar et al., 2003; WHO, 2003;
Maschinen et al., 2005). A global case-fatality ratio of 11% was
recorded (WHO, 2003). World Health Organization (WHO) announced that the
last chain of human transmission was broken on 5 July 2003. Since 2004,
there have not been any known cases of SARS reported anywhere in the
world (CDC, 2017). (Cheng, et al., 2020)
The incubation period of SARS is generally between 2– 12 days
(Maschinen et al., 2005) which was estimated to be 6.4 days with mean
incubation time of 3-5. The disease usually presents with fever, chills,
dry cough, malaise, headache, myalgia and dyspnoea; sore throat,
rhinorrhoea, vomiting and diarrhoea, symptoms may mimic other
respiratory diseases such as influenza, pneumonia or bronchitis (Hui et
al., 2004).
Detection of SARS CoV using real time polymerase chain reaction (RT-PCR)
was not reliable at early stage of the disease (Kang et al., 2005),
whereas serologic confirmation takes more than 2 weeks to achieve good
result. Serum quantitative assessment of SARS-CoV RNA with RT-PCR
constitutes only about 80% result at early days of infection (Hui et
al., 2004).
At the end of the year 2019, a novel coronavirus was identified in China
presenting with respiratory distress that mimic pneumonia (Mcintosh and
Martin, 2020) that later disseminated into Asia, Australia, Africa, and
European regions, and subsequently spread worldwide into different
countries including Japan, Italy, Germany, South Africa, Singapore,
United Kingdom and the Unites States (Elflein, 2020;Wu et al., 2020).
The virus was initially called 2019-nCoV-2 and later renamed as severe
acute respiratory syndrome virus type 2 (SARS-CoV-2) and the disease
called corona virus disease 2019 (COVID-19) in February 2019 by the WHO
(McIntosh and Martin, 2020) and subsequently declared as world
emergency. COVID-19 has the ability to spread rapidly having impact
socioeconomically and medically around the Globe (CDC, 2019; FDA, 2020).
The disease affect commonly the middle age, older individuals and
immunosuppressed, however, the later have the likelihood of severe
disease. It has incubation period of 2-14 days following exposure, most
cases occurring 4-5 days (McIntosh and Martin, 2020) with most patients
being asymptomatic at the initial stage (Fuk-Woo et al., 2020; Shi et
al., 2020). Many individuals present with high fever, fatigue, dry cough
and myalgia; dyspnoea and hypoxia that progress to acute respiratory
distress syndrome (ARDS) results, and subsequently organs failure (Wu et
al., 2020). Currently (as at May 9), COVID-19 accounts for over 4.8
million cases, more than 316, 000 deaths, over 1.85 million recoveries
and 2.5 estimated infection rate in about 216 countries and territories
worldwide (ECDC, 2020a; WHO, 2020). Higher cases (over 1.87 million)
with 165,995 deaths were reported in the European region and the lowest
incidence being reported in Oceanian region with as low as 8,440 cases,
about 126 deaths and over 8,000 recoveries). About 589.9 cases per
million cases and 40 death per million population have been reported
Globally (CDC, 2020; ECDC, 2020; Elflein, 2020; Roser et al., 2020; WHO,
2020).
Generally, viral infection can be diagnosed in the laboratory through
detection of viruses from nasal swab, pharyngeal swab, broncho-alveolar
fluids, sputum and or bronchial aspirates and blood by Electron
microscopy, viral antigens, nucleic acid, specific antibodies and by
isolation (James, 2017; Huang et al., 2020). Detection of nucleic acid
is achieved by polymeraase chain reaction (PCR), i.e nucleic acid
amplification test (NAAT) whereas antigen and antibody are detected by
serologic techniques such as Enzyme Immunoassay - ELISA, Serum
neutrallisation assay, Western blotting, Immunodiffusion,
Immunoflourescence, haemagglutination inhibition assay and Class
specific antibody assay (Reller & Weinstein, 2000; James, 2017).
Similar specimen and procedures apply to common respiratory viruses such
as adenoviruses, parainfluenza virus, avian influenza, MERS-CoV
respiratory syncytial virus, influenza virus including COVID-19 and
SARS-CoV (Huang et al., 2020). SARS-CoVs were known to spread very fast,
hence the need to have a method of detection that is easier, faster,
reliable and economically adaptable more than the currently used
techniques especially at point of care.